diff --git a/packages/jael/jael/bin/jaelfmt.dart b/packages/jael/jael/bin/jaelfmt.dart
index e3569c51..c4935c9c 100644
--- a/packages/jael/jael/bin/jaelfmt.dart
+++ b/packages/jael/jael/bin/jaelfmt.dart
@@ -41,7 +41,7 @@ main(List<String> args) async {
     if (argResults.rest.isEmpty) {
       var text = await stdin.transform(utf8.decoder).join();
       var result =
-          await format(argResults['stdin-name'] as String, text, argResults);
+          await format(argResults['stdin-name'] as String?, text, argResults);
       if (result != null) print(result);
     } else {
       for (var arg in argResults.rest) {
@@ -91,14 +91,14 @@ Future<void> formatStat(
 
 Future<void> formatFile(File file, ArgResults argResults) async {
   var content = await file.readAsString();
-  var formatted = await format(file.path, content, argResults);
+  var formatted = format(file.path, content, argResults);
   if (formatted == null) return;
   if (argResults['overwrite'] as bool) {
     if (formatted != content) {
       if (argResults['dry-run'] as bool) {
         print('Would have formatted ${file.path}');
       } else {
-        await file.writeAsStringSync(formatted);
+        file.writeAsStringSync(formatted);
         print('Formatted ${file.path}');
       }
     } else {
@@ -109,7 +109,7 @@ Future<void> formatFile(File file, ArgResults argResults) async {
   }
 }
 
-String format(String filename, String content, ArgResults argResults) {
+String? format(String? filename, String content, ArgResults argResults) {
   var errored = false;
   var doc = parseDocument(content, sourceUrl: filename, onError: (e) {
     stderr.writeln(e);
@@ -118,7 +118,7 @@ String format(String filename, String content, ArgResults argResults) {
   if (errored) return null;
   var fmt = JaelFormatter(
       int.parse(argResults['tab-size'] as String),
-      argResults['insert-spaces'] as bool,
+      argResults['insert-spaces'] as bool?,
       int.parse(argResults['line-length'] as String));
   return fmt.apply(doc);
 }
diff --git a/packages/jael/jael/lib/src/ast/array.dart b/packages/jael/jael/lib/src/ast/array.dart
index aff752b3..d4f93a1e 100644
--- a/packages/jael/jael/lib/src/ast/array.dart
+++ b/packages/jael/jael/lib/src/ast/array.dart
@@ -3,39 +3,39 @@ import 'expression.dart';
 import 'token.dart';
 
 class Array extends Expression {
-  final Token lBracket, rBracket;
+  final Token? lBracket, rBracket;
   final List<Expression> items;
 
   Array(this.lBracket, this.rBracket, this.items);
 
   @override
-  compute(scope) => items.map((e) => e.compute(scope)).toList();
+  List compute(scope) => items.map((e) => e.compute(scope)).toList();
 
   @override
   FileSpan get span {
     return items
-        .fold<FileSpan>(lBracket.span, (out, i) => out.expand(i.span))
-        .expand(rBracket.span);
+        .fold<FileSpan?>(lBracket!.span, (out, i) => out!.expand(i.span!))!
+        .expand(rBracket!.span!);
   }
 }
 
 class IndexerExpression extends Expression {
-  final Expression target, indexer;
-  final Token lBracket, rBracket;
+  final Expression? target, indexer;
+  final Token? lBracket, rBracket;
 
   IndexerExpression(this.target, this.lBracket, this.indexer, this.rBracket);
 
   @override
   FileSpan get span {
-    return target.span
-        .expand(lBracket.span)
-        .expand(indexer.span)
-        .expand(rBracket.span);
+    return target!.span!
+        .expand(lBracket!.span!)
+        .expand(indexer!.span!)
+        .expand(rBracket!.span!);
   }
 
   @override
-  compute(scope) {
-    var a = target.compute(scope), b = indexer.compute(scope);
+  dynamic compute(scope) {
+    var a = target!.compute(scope), b = indexer!.compute(scope);
     return a[b];
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/ast_node.dart b/packages/jael/jael/lib/src/ast/ast_node.dart
index c48971da..29f2bd67 100644
--- a/packages/jael/jael/lib/src/ast/ast_node.dart
+++ b/packages/jael/jael/lib/src/ast/ast_node.dart
@@ -1,5 +1,5 @@
 import 'package:source_span/source_span.dart';
 
 abstract class AstNode {
-  FileSpan get span;
+  FileSpan? get span;
 }
diff --git a/packages/jael/jael/lib/src/ast/attribute.dart b/packages/jael/jael/lib/src/ast/attribute.dart
index f06d76e8..1bbbf599 100644
--- a/packages/jael/jael/lib/src/ast/attribute.dart
+++ b/packages/jael/jael/lib/src/ast/attribute.dart
@@ -6,22 +6,22 @@ import 'string.dart';
 import 'token.dart';
 
 class Attribute extends AstNode {
-  final Identifier id;
-  final StringLiteral string;
-  final Token equals, nequ;
-  final Expression value;
+  final Identifier? id;
+  final StringLiteral? string;
+  final Token? equals, nequ;
+  final Expression? value;
 
   Attribute(this.id, this.string, this.equals, this.nequ, this.value);
 
   bool get isRaw => nequ != null;
 
-  Expression get nameNode => id ?? string;
+  Expression? get nameNode => id ?? string;
 
-  String get name => string?.value ?? id.name;
+  String get name => string?.value ?? id!.name;
 
   @override
-  FileSpan get span {
-    if (equals == null) return nameNode.span;
-    return nameNode.span.expand(equals?.span ?? nequ.span).expand(value.span);
+  FileSpan? get span {
+    if (equals == null) return nameNode!.span;
+    return nameNode!.span!.expand(equals?.span ?? nequ!.span!).expand(value!.span!);
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/binary.dart b/packages/jael/jael/lib/src/ast/binary.dart
index 75ed2261..908f3f59 100644
--- a/packages/jael/jael/lib/src/ast/binary.dart
+++ b/packages/jael/jael/lib/src/ast/binary.dart
@@ -3,14 +3,14 @@ import 'expression.dart';
 import 'token.dart';
 
 class BinaryExpression extends Expression {
-  final Expression left, right;
-  final Token operator;
+  final Expression? left, right;
+  final Token? operator;
 
   BinaryExpression(this.left, this.operator, this.right);
 
   @override
   compute(scope) {
-    var l = left.compute(scope), r = right.compute(scope);
+    var l = left!.compute(scope), r = right!.compute(scope);
 
     switch (operator?.type) {
       case TokenType.asterisk:
@@ -43,5 +43,5 @@ class BinaryExpression extends Expression {
   }
 
   @override
-  FileSpan get span => left.span.expand(operator.span).expand(right.span);
+  FileSpan get span => left!.span!.expand(operator!.span!).expand(right!.span!);
 }
diff --git a/packages/jael/jael/lib/src/ast/call.dart b/packages/jael/jael/lib/src/ast/call.dart
index 0e1272a9..e19551c7 100644
--- a/packages/jael/jael/lib/src/ast/call.dart
+++ b/packages/jael/jael/lib/src/ast/call.dart
@@ -6,8 +6,8 @@ import 'identifier.dart';
 import 'token.dart';
 
 class Call extends Expression {
-  final Expression target;
-  final Token lParen, rParen;
+  final Expression? target;
+  final Token? lParen, rParen;
   final List<Expression> arguments;
   final List<NamedArgument> namedArguments;
 
@@ -17,10 +17,10 @@ class Call extends Expression {
   @override
   FileSpan get span {
     return arguments
-        .fold<FileSpan>(target.span, (out, a) => out.expand(a.span))
-        .expand(namedArguments.fold<FileSpan>(
-            lParen.span, (out, a) => out.expand(a.span)))
-        .expand(rParen.span);
+        .fold<FileSpan?>(target!.span, (out, a) => out!.expand(a.span!))!
+        .expand(namedArguments.fold<FileSpan?>(
+            lParen!.span, (out, a) => out!.expand(a.span))!)
+        .expand(rParen!.span!);
   }
 
   List computePositional(SymbolTable scope) =>
@@ -34,7 +34,7 @@ class Call extends Expression {
 
   @override
   compute(scope) {
-    var callee = target.compute(scope);
+    var callee = target!.compute(scope);
     var args = computePositional(scope);
     var named = computeNamed(scope);
 
@@ -44,13 +44,13 @@ class Call extends Expression {
 
 class NamedArgument extends AstNode {
   final Identifier name;
-  final Token colon;
+  final Token? colon;
   final Expression value;
 
   NamedArgument(this.name, this.colon, this.value);
 
   @override
   FileSpan get span {
-    return name.span.expand(colon.span).expand(value.span);
+    return name.span!.expand(colon!.span!).expand(value.span!);
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/conditional.dart b/packages/jael/jael/lib/src/ast/conditional.dart
index c54f6358..d3491193 100644
--- a/packages/jael/jael/lib/src/ast/conditional.dart
+++ b/packages/jael/jael/lib/src/ast/conditional.dart
@@ -3,29 +3,29 @@ import 'expression.dart';
 import 'token.dart';
 
 class Conditional extends Expression {
-  final Expression condition, ifTrue, ifFalse;
-  final Token question, colon;
+  final Expression? condition, ifTrue, ifFalse;
+  final Token? question, colon;
 
   Conditional(
       this.condition, this.question, this.ifTrue, this.colon, this.ifFalse);
 
   @override
   FileSpan get span {
-    return condition.span
-        .expand(question.span)
-        .expand(ifTrue.span)
-        .expand(colon.span)
-        .expand(ifFalse.span);
+    return condition!.span!
+        .expand(question!.span!)
+        .expand(ifTrue!.span!)
+        .expand(colon!.span!)
+        .expand(ifFalse!.span!);
   }
 
   @override
   compute(scope) {
-    var v = condition.compute(scope) as bool;
+    var v = condition!.compute(scope) as bool?;
 
     if (scope.resolve('!strict!')?.value == false) {
       v = v == true;
     }
 
-    return v ? ifTrue.compute(scope) : ifFalse.compute(scope);
+    return v! ? ifTrue!.compute(scope) : ifFalse!.compute(scope);
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/document.dart b/packages/jael/jael/lib/src/ast/document.dart
index b59a371e..04c8198e 100644
--- a/packages/jael/jael/lib/src/ast/document.dart
+++ b/packages/jael/jael/lib/src/ast/document.dart
@@ -6,40 +6,40 @@ import 'string.dart';
 import 'token.dart';
 
 class Document extends AstNode {
-  final Doctype doctype;
+  final Doctype? doctype;
   final Element root;
 
   Document(this.doctype, this.root);
 
   @override
-  FileSpan get span {
+  FileSpan? get span {
     if (doctype == null) return root.span;
-    return doctype.span.expand(root.span);
+    return doctype!.span.expand(root.span!);
   }
 }
 
 class HtmlComment extends ElementChild {
-  final Token htmlComment;
+  final Token? htmlComment;
 
   HtmlComment(this.htmlComment);
 
   @override
-  FileSpan get span => htmlComment.span;
+  FileSpan? get span => htmlComment!.span;
 }
 
 class Text extends ElementChild {
-  final Token text;
+  final Token? text;
 
   Text(this.text);
 
   @override
-  FileSpan get span => text.span;
+  FileSpan? get span => text!.span;
 }
 
 class Doctype extends AstNode {
-  final Token lt, doctype, gt;
-  final Identifier html, public;
-  final StringLiteral name, url;
+  final Token? lt, doctype, gt;
+  final Identifier? html, public;
+  final StringLiteral? name, url;
 
   Doctype(this.lt, this.doctype, this.html, this.public, this.name, this.url,
       this.gt);
@@ -47,14 +47,14 @@ class Doctype extends AstNode {
   @override
   FileSpan get span {
     if (public == null) {
-      return lt.span.expand(doctype.span).expand(html.span).expand(gt.span);
+      return lt!.span!.expand(doctype!.span!).expand(html!.span!).expand(gt!.span!);
     }
-    return lt.span
-        .expand(doctype.span)
-        .expand(html.span)
-        .expand(public.span)
-        .expand(name.span)
-        .expand(url.span)
-        .expand(gt.span);
+    return lt!.span!
+        .expand(doctype!.span!)
+        .expand(html!.span!)
+        .expand(public!.span!)
+        .expand(name!.span!)
+        .expand(url!.span!)
+        .expand(gt!.span!);
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/element.dart b/packages/jael/jael/lib/src/ast/element.dart
index bdfb5653..5a359061 100644
--- a/packages/jael/jael/lib/src/ast/element.dart
+++ b/packages/jael/jael/lib/src/ast/element.dart
@@ -1,3 +1,4 @@
+import 'package:collection/collection.dart' show IterableExtension;
 import 'package:source_span/source_span.dart';
 import 'ast_node.dart';
 import 'attribute.dart';
@@ -12,7 +13,7 @@ class TextNode extends ElementChild {
   TextNode(this.text);
 
   @override
-  FileSpan get span => text.span;
+  FileSpan? get span => text.span;
 }
 
 abstract class Element extends ElementChild {
@@ -38,12 +39,12 @@ abstract class Element extends ElementChild {
 
   Iterable<ElementChild> get children;
 
-  Attribute getAttribute(String name) =>
-      attributes.firstWhere((a) => a.name == name, orElse: () => null);
+  Attribute? getAttribute(String name) =>
+      attributes.firstWhereOrNull((a) => a.name == name);
 }
 
 class SelfClosingElement extends Element {
-  final Token lt, slash, gt;
+  final Token? lt, slash, gt;
 
   final Identifier tagName;
 
@@ -58,15 +59,15 @@ class SelfClosingElement extends Element {
   @override
   FileSpan get span {
     var start = attributes.fold<FileSpan>(
-        lt.span.expand(tagName.span), (out, a) => out.expand(a.span));
+        lt!.span!.expand(tagName.span!), (out, a) => out.expand(a.span!));
     return slash != null
-        ? start.expand(slash.span).expand(gt.span)
-        : start.expand(gt.span);
+        ? start.expand(slash!.span!).expand(gt!.span!)
+        : start.expand(gt!.span!);
   }
 }
 
 class RegularElement extends Element {
-  final Token lt, gt, lt2, slash, gt2;
+  final Token? lt, gt, lt2, slash, gt2;
 
   final Identifier tagName, tagName2;
 
@@ -81,16 +82,16 @@ class RegularElement extends Element {
   FileSpan get span {
     var openingTag = attributes
         .fold<FileSpan>(
-            lt.span.expand(tagName.span), (out, a) => out.expand(a.span))
-        .expand(gt.span);
+            lt!.span!.expand(tagName.span!), (out, a) => out.expand(a.span!))
+        .expand(gt!.span!);
 
     if (gt2 == null) return openingTag;
 
     return children
-        .fold<FileSpan>(openingTag, (out, c) => out.expand(c.span))
-        .expand(lt2.span)
-        .expand(slash.span)
-        .expand(tagName2.span)
-        .expand(gt2.span);
+        .fold<FileSpan>(openingTag, (out, c) => out.expand(c.span!))
+        .expand(lt2!.span!)
+        .expand(slash!.span!)
+        .expand(tagName2.span!)
+        .expand(gt2!.span!);
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/error.dart b/packages/jael/jael/lib/src/ast/error.dart
index f931a126..66784d5b 100644
--- a/packages/jael/jael/lib/src/ast/error.dart
+++ b/packages/jael/jael/lib/src/ast/error.dart
@@ -3,15 +3,15 @@ import 'package:source_span/source_span.dart';
 class JaelError extends Error {
   final JaelErrorSeverity severity;
   final String message;
-  final FileSpan span;
+  final FileSpan? span;
 
   JaelError(this.severity, this.message, this.span);
 
   @override
   String toString() {
     var label = severity == JaelErrorSeverity.warning ? 'warning' : 'error';
-    return '$label: ${span.start.toolString}: $message\n' +
-        span.highlight(color: true);
+    return '$label: ${span!.start.toolString}: $message\n' +
+        span!.highlight(color: true);
   }
 }
 
diff --git a/packages/jael/jael/lib/src/ast/expression.dart b/packages/jael/jael/lib/src/ast/expression.dart
index 0e0f8147..851312b7 100644
--- a/packages/jael/jael/lib/src/ast/expression.dart
+++ b/packages/jael/jael/lib/src/ast/expression.dart
@@ -4,30 +4,30 @@ import 'ast_node.dart';
 import 'token.dart';
 
 abstract class Expression extends AstNode {
-  compute(SymbolTable scope);
+  dynamic compute(SymbolTable scope);
 }
 
 abstract class Literal extends Expression {}
 
 class Negation extends Expression {
-  final Token exclamation;
-  final Expression expression;
+  final Token? exclamation;
+  final Expression? expression;
 
   Negation(this.exclamation, this.expression);
 
   @override
   FileSpan get span {
-    return exclamation.span.expand(expression.span);
+    return exclamation!.span!.expand(expression!.span!);
   }
 
   @override
   compute(SymbolTable scope) {
-    var v = expression.compute(scope) as bool;
+    var v = expression!.compute(scope) as bool?;
 
     if (scope.resolve('!strict!')?.value == false) {
       v = v == true;
     }
 
-    return !v;
+    return !v!;
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/identifier.dart b/packages/jael/jael/lib/src/ast/identifier.dart
index e2f8c6fd..da95c2d4 100644
--- a/packages/jael/jael/lib/src/ast/identifier.dart
+++ b/packages/jael/jael/lib/src/ast/identifier.dart
@@ -4,7 +4,7 @@ import 'expression.dart';
 import 'token.dart';
 
 class Identifier extends Expression {
-  final Token id;
+  final Token? id;
 
   Identifier(this.id);
 
@@ -23,25 +23,25 @@ class Identifier extends Expression {
           if (scope.resolve('!strict!')?.value == false) return null;
           throw ArgumentError('The name "$name" does not exist in this scope.');
         }
-        return scope.resolve(name).value;
+        return scope.resolve(name)!.value;
     }
   }
 
-  String get name => id.span.text;
+  String get name => id!.span!.text;
 
   @override
-  FileSpan get span => id.span;
+  FileSpan? get span => id!.span;
 }
 
 class SyntheticIdentifier extends Identifier {
   @override
   final String name;
 
-  SyntheticIdentifier(this.name, [Token token]) : super(token);
+  SyntheticIdentifier(this.name, [Token? token]) : super(token);
 
   @override
-  FileSpan get span {
-    if (id != null) return id.span;
+  FileSpan? get span {
+    if (id != null) return id!.span;
     throw UnsupportedError('Cannot get the span of a SyntheticIdentifier.');
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/interpolation.dart b/packages/jael/jael/lib/src/ast/interpolation.dart
index 2dacb790..331011ba 100644
--- a/packages/jael/jael/lib/src/ast/interpolation.dart
+++ b/packages/jael/jael/lib/src/ast/interpolation.dart
@@ -4,15 +4,15 @@ import 'expression.dart';
 import 'token.dart';
 
 class Interpolation extends ElementChild {
-  final Token doubleCurlyL, doubleCurlyR;
+  final Token? doubleCurlyL, doubleCurlyR;
   final Expression expression;
 
   Interpolation(this.doubleCurlyL, this.expression, this.doubleCurlyR);
 
-  bool get isRaw => doubleCurlyL.span.text.endsWith('-');
+  bool get isRaw => doubleCurlyL!.span!.text.endsWith('-');
 
   @override
   FileSpan get span {
-    return doubleCurlyL.span.expand(expression.span).expand(doubleCurlyR.span);
+    return doubleCurlyL!.span!.expand(expression.span!).expand(doubleCurlyR!.span!);
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/map.dart b/packages/jael/jael/lib/src/ast/map.dart
index 8f457f3b..23078a1e 100644
--- a/packages/jael/jael/lib/src/ast/map.dart
+++ b/packages/jael/jael/lib/src/ast/map.dart
@@ -5,7 +5,7 @@ import 'identifier.dart';
 import 'token.dart';
 
 class MapLiteral extends Literal {
-  final Token lCurly, rCurly;
+  final Token? lCurly, rCurly;
   final List<KeyValuePair> pairs;
 
   MapLiteral(this.lCurly, this.pairs, this.rCurly);
@@ -17,14 +17,14 @@ class MapLiteral extends Literal {
 
       if (p.colon == null) {
         if (p.key is! Identifier) {
-          key = value = p.key.compute(scope);
+          key = value = p.key!.compute(scope);
         } else {
           key = (p.key as Identifier).name;
-          value = p.key.compute(scope);
+          value = p.key!.compute(scope);
         }
       } else {
-        key = p.key.compute(scope);
-        value = p.value.compute(scope);
+        key = p.key!.compute(scope);
+        value = p.value!.compute(scope);
       }
 
       return out..[key] = value;
@@ -34,20 +34,20 @@ class MapLiteral extends Literal {
   @override
   FileSpan get span {
     return pairs
-        .fold<FileSpan>(lCurly.span, (out, p) => out.expand(p.span))
-        .expand(rCurly.span);
+        .fold<FileSpan?>(lCurly!.span, (out, p) => out!.expand(p.span!))!
+        .expand(rCurly!.span!);
   }
 }
 
 class KeyValuePair extends AstNode {
-  final Expression key, value;
-  final Token colon;
+  final Expression? key, value;
+  final Token? colon;
 
   KeyValuePair(this.key, this.colon, this.value);
 
   @override
-  FileSpan get span {
-    if (colon == null) return key.span;
-    return colon.span.expand(colon.span).expand(value.span);
+  FileSpan? get span {
+    if (colon == null) return key!.span;
+    return colon!.span!.expand(colon!.span!).expand(value!.span!);
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/member.dart b/packages/jael/jael/lib/src/ast/member.dart
index 1bac5e50..86751fbe 100644
--- a/packages/jael/jael/lib/src/ast/member.dart
+++ b/packages/jael/jael/lib/src/ast/member.dart
@@ -6,19 +6,19 @@ import 'identifier.dart';
 import 'token.dart';
 
 class MemberExpression extends Expression {
-  final Expression expression;
-  final Token op;
+  final Expression? expression;
+  final Token? op;
   final Identifier name;
 
   MemberExpression(this.expression, this.op, this.name);
 
   @override
   compute(SymbolTable scope) {
-    var target = expression.compute(scope);
-    if (op.span.text == '?.' && target == null) return null;
+    var target = expression!.compute(scope);
+    if (op!.span!.text == '?.' && target == null) return null;
     return reflect(target).getField(Symbol(name.name)).reflectee;
   }
 
   @override
-  FileSpan get span => expression.span.expand(op.span).expand(name.span);
+  FileSpan get span => expression!.span!.expand(op!.span!).expand(name.span!);
 }
diff --git a/packages/jael/jael/lib/src/ast/new.dart b/packages/jael/jael/lib/src/ast/new.dart
index d13892ce..57ec6be2 100644
--- a/packages/jael/jael/lib/src/ast/new.dart
+++ b/packages/jael/jael/lib/src/ast/new.dart
@@ -6,17 +6,17 @@ import 'member.dart';
 import 'token.dart';
 
 class NewExpression extends Expression {
-  final Token $new;
+  final Token? $new;
   final Call call;
 
   NewExpression(this.$new, this.call);
 
   @override
-  FileSpan get span => $new.span.expand(call.span);
+  FileSpan get span => $new!.span!.expand(call.span);
 
   @override
   compute(scope) {
-    var targetType = call.target.compute(scope);
+    var targetType = call.target!.compute(scope);
     var positional = call.computePositional(scope);
     var named = call.computeNamed(scope);
     var name = '';
diff --git a/packages/jael/jael/lib/src/ast/number.dart b/packages/jael/jael/lib/src/ast/number.dart
index 3ef3eab5..c91dc48f 100644
--- a/packages/jael/jael/lib/src/ast/number.dart
+++ b/packages/jael/jael/lib/src/ast/number.dart
@@ -4,13 +4,13 @@ import 'expression.dart';
 import 'token.dart';
 
 class NumberLiteral extends Literal {
-  final Token number;
-  num _value;
+  final Token? number;
+  num? _value;
 
   NumberLiteral(this.number);
 
   @override
-  FileSpan get span => number.span;
+  FileSpan? get span => number!.span;
 
   static num parse(String value) {
     var e = value.indexOf('E');
@@ -25,23 +25,23 @@ class NumberLiteral extends Literal {
 
   @override
   compute(scope) {
-    return _value ??= parse(number.span.text);
+    return _value ??= parse(number!.span!.text);
   }
 }
 
 class HexLiteral extends Literal {
-  final Token hex;
-  num _value;
+  final Token? hex;
+  num? _value;
 
   HexLiteral(this.hex);
 
   @override
-  FileSpan get span => hex.span;
+  FileSpan? get span => hex!.span;
 
   static num parse(String value) => int.parse(value.substring(2), radix: 16);
 
   @override
   compute(scope) {
-    return _value ??= parse(hex.span.text);
+    return _value ??= parse(hex!.span!.text);
   }
 }
diff --git a/packages/jael/jael/lib/src/ast/string.dart b/packages/jael/jael/lib/src/ast/string.dart
index cf7163e3..3a87c3ae 100644
--- a/packages/jael/jael/lib/src/ast/string.dart
+++ b/packages/jael/jael/lib/src/ast/string.dart
@@ -6,13 +6,13 @@ import 'expression.dart';
 import 'token.dart';
 
 class StringLiteral extends Literal {
-  final Token string;
+  final Token? string;
   final String value;
 
   StringLiteral(this.string, this.value);
 
   static String parseValue(Token string) {
-    var text = string.span.text.substring(1, string.span.text.length - 1);
+    var text = string.span!.text.substring(1, string.span!.text.length - 1);
     var codeUnits = text.codeUnits;
     var buf = StringBuffer();
 
@@ -71,5 +71,5 @@ class StringLiteral extends Literal {
   }
 
   @override
-  FileSpan get span => string.span;
+  FileSpan? get span => string!.span;
 }
diff --git a/packages/jael/jael/lib/src/ast/token.dart b/packages/jael/jael/lib/src/ast/token.dart
index 0e4d4a04..54deaf6b 100644
--- a/packages/jael/jael/lib/src/ast/token.dart
+++ b/packages/jael/jael/lib/src/ast/token.dart
@@ -2,14 +2,14 @@ import 'package:source_span/source_span.dart';
 
 class Token {
   final TokenType type;
-  final FileSpan span;
-  final Match match;
+  final FileSpan? span;
+  final Match? match;
 
   Token(this.type, this.span, this.match);
 
   @override
   String toString() {
-    return '${span.start.toolString}: "${span.text}" => $type';
+    return '${span!.start.toolString}: "${span!.text}" => $type';
   }
 }
 
diff --git a/packages/jael/jael/lib/src/formatter.dart b/packages/jael/jael/lib/src/formatter.dart
index 9b62f9e2..3b46ed7c 100644
--- a/packages/jael/jael/lib/src/formatter.dart
+++ b/packages/jael/jael/lib/src/formatter.dart
@@ -3,11 +3,11 @@ import 'ast/ast.dart';
 /// Jael formatter
 class JaelFormatter {
   final num tabSize;
-  final bool insertSpaces;
+  final bool? insertSpaces;
   final int maxLineLength;
   var _buffer = StringBuffer();
   int _level = 0;
-  String _spaces;
+  String? _spaces;
 
   static String _spaceString(int tabSize) {
     var b = StringBuffer();
@@ -18,7 +18,7 @@ class JaelFormatter {
   }
 
   JaelFormatter(this.tabSize, this.insertSpaces, this.maxLineLength) {
-    _spaces = insertSpaces ? _spaceString(tabSize.toInt()) : '\t';
+    _spaces = insertSpaces! ? _spaceString(tabSize.toInt()) : '\t';
   }
 
   void _indent() {
@@ -38,20 +38,20 @@ class JaelFormatter {
   int get _spaceLength {
     var out = 0;
     for (int i = 0; i < _level; i++) {
-      out += _spaces.length;
+      out += _spaces!.length;
     }
     return out;
   }
 
-  String apply(Document document) {
+  String apply(Document? document) {
     if (document?.doctype != null) {
       _buffer.write('<!doctype');
 
-      if (document.doctype.html != null) _buffer.write(' html');
-      if (document.doctype.public != null) _buffer.write(' public');
+      if (document!.doctype!.html != null) _buffer.write(' html');
+      if (document.doctype!.public != null) _buffer.write(' public');
 
-      if (document.doctype.url != null) {
-        _buffer.write('${document.doctype.url}');
+      if (document.doctype!.url != null) {
+        _buffer.write('${document.doctype!.url}');
       }
 
       _buffer.writeln('>');
@@ -62,7 +62,7 @@ class JaelFormatter {
     return _buffer.toString().trim();
   }
 
-  int _formatChild(ElementChild child, int lineLength,
+  int _formatChild(ElementChild? child, int lineLength,
       {bool isFirst = false, bool isLast = false}) {
     if (child == null) {
       return lineLength;
@@ -72,11 +72,11 @@ class JaelFormatter {
       var b = StringBuffer('{{');
       if (child.isRaw) b.write('-');
       b.write(' ');
-      b.write(child.expression.span.text.trim());
+      b.write(child.expression.span!.text.trim());
       b.write(' }}');
       s = b.toString();
     } else {
-      s = child.span.text;
+      s = child.span!.text;
     }
     if (isFirst) {
       s = s.trimLeft();
@@ -145,7 +145,7 @@ class JaelFormatter {
     _indent();
     var lll = _spaceLength;
     var i = 1;
-    ElementChild last;
+    ElementChild? last;
     for (var c in element.children) {
       if (lll == _spaceLength && c is! Element) {
         _applySpacing();
@@ -186,7 +186,7 @@ class JaelFormatter {
       } else {
         if (attr.nequ != null) b.write('!=');
         if (attr.equals != null) b.write('=');
-        b.write(attr.value.span.text);
+        b.write(attr.value!.span!.text);
       }
     }
     return b.toString();
diff --git a/packages/jael/jael/lib/src/renderer.dart b/packages/jael/jael/lib/src/renderer.dart
index 62b36442..43d4cd5c 100644
--- a/packages/jael/jael/lib/src/renderer.dart
+++ b/packages/jael/jael/lib/src/renderer.dart
@@ -1,13 +1,14 @@
 import 'dart:convert';
 import 'package:code_buffer/code_buffer.dart';
+import 'package:collection/collection.dart' show IterableExtension;
 import 'package:symbol_table/symbol_table.dart';
 import 'ast/ast.dart';
 import 'text/parser.dart';
 import 'text/scanner.dart';
 
 /// Parses a Jael document.
-Document parseDocument(String text,
-    {sourceUrl, bool asDSX = false, void onError(JaelError error)}) {
+Document? parseDocument(String text,
+    {sourceUrl, bool asDSX = false, void onError(JaelError error)?}) {
   var scanner = scan(text, sourceUrl: sourceUrl, asDSX: asDSX);
 
   //scanner.tokens.forEach(print);
@@ -55,12 +56,12 @@ class Renderer {
         ..writeln('<li>')
         ..indent()
         ..writeln(
-            '<b>$type:</b> ${error.span.start.toolString}: ${error.message}')
+            '<b>$type:</b> ${error.span!.start.toolString}: ${error.message}')
         ..writeln('<br>')
         ..writeln(
           '<span style="color: red;">' +
               htmlEscape
-                  .convert(error.span.highlight(color: false))
+                  .convert(error.span!.highlight(color: false))
                   .replaceAll('\n', '<br>') +
               '</span>',
         )
@@ -83,7 +84,7 @@ class Renderer {
       {bool strictResolution = true}) {
     scope.create('!strict!', value: strictResolution != false);
 
-    if (document.doctype != null) buffer.writeln(document.doctype.span.text);
+    if (document.doctype != null) buffer.writeln(document.doctype!.span.text);
     renderElement(
         document.root, buffer, scope, document.doctype?.public == null);
   }
@@ -177,15 +178,15 @@ class Renderer {
     var attribute = element.attributes.singleWhere((a) => a.name == 'for-each');
     if (attribute.value == null) return;
 
-    var asAttribute = element.attributes
-        .firstWhere((a) => a.name == 'as', orElse: () => null);
-    var indexAsAttribute = element.attributes
-        .firstWhere((a) => a.name == 'index-as', orElse: () => null);
+    var asAttribute =
+        element.attributes.firstWhereOrNull((a) => a.name == 'as');
+    var indexAsAttribute =
+        element.attributes.firstWhereOrNull((a) => a.name == 'index-as');
     var alias = asAttribute?.value?.compute(scope)?.toString() ?? 'item';
     var indexAs = indexAsAttribute?.value?.compute(scope)?.toString() ?? 'i';
     var otherAttributes = element.attributes.where(
         (a) => a.name != 'for-each' && a.name != 'as' && a.name != 'index-as');
-    Element strippedElement;
+    late Element strippedElement;
 
     if (element is SelfClosingElement) {
       strippedElement = SelfClosingElement(element.lt, element.tagName,
@@ -204,7 +205,7 @@ class Renderer {
     }
 
     int i = 0;
-    for (var item in attribute.value.compute(scope)) {
+    for (var item in attribute.value!.compute(scope)) {
       var childScope = scope.createChild(values: {alias: item, indexAs: i++});
       renderElement(strippedElement, buffer, childScope, html5);
     }
@@ -214,7 +215,7 @@ class Renderer {
       Element element, CodeBuffer buffer, SymbolTable scope, bool html5) {
     var attribute = element.attributes.singleWhere((a) => a.name == 'if');
 
-    var vv = attribute.value.compute(scope);
+    var vv = attribute.value!.compute(scope);
 
     if (scope.resolve('!strict!')?.value == false) {
       vv = vv == true;
@@ -225,7 +226,7 @@ class Renderer {
     if (!v) return;
 
     var otherAttributes = element.attributes.where((a) => a.name != 'if');
-    Element strippedElement;
+    late Element strippedElement;
 
     if (element is SelfClosingElement) {
       strippedElement = SelfClosingElement(element.lt, element.tagName,
@@ -263,7 +264,7 @@ class Renderer {
   void renderSwitch(
       Element element, CodeBuffer buffer, SymbolTable scope, bool html5) {
     var value = element.attributes
-        .firstWhere((a) => a.name == 'value', orElse: () => null)
+        .firstWhereOrNull((a) => a.name == 'value')
         ?.value
         ?.compute(scope);
 
@@ -273,7 +274,7 @@ class Renderer {
 
     for (var child in cases) {
       var comparison = child.attributes
-          .firstWhere((a) => a.name == 'value', orElse: () => null)
+          .firstWhereOrNull((a) => a.name == 'value')
           ?.value
           ?.compute(scope);
       if (comparison == value) {
@@ -287,11 +288,10 @@ class Renderer {
       }
     }
 
-    var defaultCase = element.children.firstWhere(
-        (c) => c is Element && c.tagName.name == 'default',
-        orElse: () => null) as Element;
+    var defaultCase = element.children.firstWhereOrNull(
+        (c) => c is Element && c.tagName.name == 'default') as Element?;
     if (defaultCase != null) {
-      for (int i = 0; i < defaultCase.children.length; i++) {
+      for (var i = 0; i < defaultCase.children.length; i++) {
         var child = defaultCase.children.elementAt(i);
         renderElementChild(element, child, buffer, scope, html5, i,
             defaultCase.children.length);
@@ -301,13 +301,13 @@ class Renderer {
 
   void renderElementChild(Element parent, ElementChild child, CodeBuffer buffer,
       SymbolTable scope, bool html5, int index, int total) {
-    if (child is Text && parent?.tagName?.name != 'textarea') {
+    if (child is Text && parent.tagName.name != 'textarea') {
       if (index == 0) {
-        buffer.write(child.span.text.trimLeft());
+        buffer.write(child.span!.text.trimLeft());
       } else if (index == total - 1) {
-        buffer.write(child.span.text.trimRight());
+        buffer.write(child.span!.text.trimRight());
       } else {
-        buffer.write(child.span.text);
+        buffer.write(child.span!.text);
       }
     } else if (child is Interpolation) {
       var value = child.expression.compute(scope);
@@ -320,7 +320,7 @@ class Renderer {
         }
       }
     } else if (child is Element) {
-      if (buffer?.lastLine?.text?.isNotEmpty == true) buffer.writeln();
+      if (buffer.lastLine?.text.isNotEmpty == true) buffer.writeln();
       renderElement(child, buffer, scope, html5);
     }
   }
@@ -331,7 +331,7 @@ class Renderer {
       Element element, CodeBuffer buffer, SymbolTable scope, bool html5) {
     if (element is! RegularElement) {
       throw JaelError(JaelErrorSeverity.error,
-          "Custom elements cannot be self-closing.", element.span);
+          'Custom elements cannot be self-closing.', element.span);
     }
 
     var name = element.getAttribute('name')?.value?.compute(scope)?.toString();
@@ -344,20 +344,20 @@ class Renderer {
     }
 
     try {
-      var p = scope.isRoot ? scope : scope.parent;
+      var p = scope.isRoot ? scope : scope.parent!;
       p.create(customElementName(name), value: element, constant: true);
     } on StateError {
       throw JaelError(
           JaelErrorSeverity.error,
           "Cannot re-define element '$name' in this scope.",
-          element.getAttribute('name').span);
+          element.getAttribute('name')!.span);
     }
   }
 
   void renderCustomElement(
       Element element, CodeBuffer buffer, SymbolTable scope, bool html5) {
-    var template = scope.resolve(customElementName(element.tagName.name)).value
-        as RegularElement;
+    var template = scope.resolve(customElementName(element.tagName.name))!.value
+        as RegularElement?;
     var renderAs = element.getAttribute('as')?.value?.compute(scope);
     var attrs = element.attributes.where((a) => a.name != 'as');
 
@@ -369,7 +369,7 @@ class Renderer {
     }
 
     if (renderAs == false) {
-      for (int i = 0; i < template.children.length; i++) {
+      for (int i = 0; i < template!.children.length; i++) {
         var child = template.children.elementAt(i);
         renderElementChild(
             element, child, buffer, scope, html5, i, element.children.length);
@@ -378,7 +378,7 @@ class Renderer {
       var tagName = renderAs?.toString() ?? 'div';
 
       var syntheticElement = RegularElement(
-          template.lt,
+          template!.lt,
           SyntheticIdentifier(tagName),
           element.attributes
               .where((a) => a.name != 'as' && !a.name.startsWith('@')),
diff --git a/packages/jael/jael/lib/src/text/parselet/infix.dart b/packages/jael/jael/lib/src/text/parselet/infix.dart
index 9c52e6af..9a5a27aa 100644
--- a/packages/jael/jael/lib/src/text/parselet/infix.dart
+++ b/packages/jael/jael/lib/src/text/parselet/infix.dart
@@ -28,12 +28,12 @@ class ConditionalParselet implements InfixParselet {
   const ConditionalParselet();
 
   @override
-  Expression parse(Parser parser, Expression left, Token token) {
+  Expression? parse(Parser parser, Expression? left, Token? token) {
     var ifTrue = parser.parseExpression(0);
 
     if (ifTrue == null) {
       parser.errors.add(JaelError(JaelErrorSeverity.error,
-          'Missing expression in conditional expression.', token.span));
+          'Missing expression in conditional expression.', token!.span));
       return null;
     }
 
@@ -48,7 +48,7 @@ class ConditionalParselet implements InfixParselet {
 
     if (ifFalse == null) {
       parser.errors.add(JaelError(JaelErrorSeverity.error,
-          'Missing expression in conditional expression.', colon.span));
+          'Missing expression in conditional expression.', colon!.span));
       return null;
     }
 
@@ -62,14 +62,14 @@ class BinaryParselet implements InfixParselet {
   const BinaryParselet(this.precedence);
 
   @override
-  Expression parse(Parser parser, Expression left, Token token) {
+  Expression? parse(Parser parser, Expression? left, Token? token) {
     var right = parser.parseExpression(precedence);
 
     if (right == null) {
-      if (token.type != TokenType.gt) {
+      if (token!.type != TokenType.gt) {
         parser.errors.add(JaelError(
             JaelErrorSeverity.error,
-            'Missing expression after operator "${token.span.text}", following expression ${left.span.text}.',
+            'Missing expression after operator "${token.span!.text}", following expression ${left!.span!.text}.',
             token.span));
       }
       return null;
@@ -86,10 +86,10 @@ class CallParselet implements InfixParselet {
   int get precedence => 19;
 
   @override
-  Expression parse(Parser parser, Expression left, Token token) {
+  Expression? parse(Parser parser, Expression? left, Token? token) {
     List<Expression> arguments = [];
     List<NamedArgument> namedArguments = [];
-    Expression argument = parser.parseExpression(0);
+    Expression? argument = parser.parseExpression(0);
 
     while (argument != null) {
       arguments.add(argument);
@@ -98,7 +98,7 @@ class CallParselet implements InfixParselet {
       argument = parser.parseExpression(0);
     }
 
-    NamedArgument namedArgument = parser.parseNamedArgument();
+    NamedArgument? namedArgument = parser.parseNamedArgument();
 
     while (namedArgument != null) {
       namedArguments.add(namedArgument);
@@ -109,7 +109,7 @@ class CallParselet implements InfixParselet {
 
     if (!parser.next(TokenType.rParen)) {
       var lastSpan = arguments.isEmpty ? null : arguments.last.span;
-      lastSpan ??= token.span;
+      lastSpan ??= token!.span;
       parser.errors.add(JaelError(JaelErrorSeverity.error,
           'Missing ")" after argument list.', lastSpan));
       return null;
@@ -126,12 +126,12 @@ class IndexerParselet implements InfixParselet {
   int get precedence => 19;
 
   @override
-  Expression parse(Parser parser, Expression left, Token token) {
+  Expression? parse(Parser parser, Expression? left, Token? token) {
     var indexer = parser.parseExpression(0);
 
     if (indexer == null) {
       parser.errors.add(JaelError(
-          JaelErrorSeverity.error, 'Missing expression after "[".', left.span));
+          JaelErrorSeverity.error, 'Missing expression after "[".', left!.span));
       return null;
     }
 
@@ -152,12 +152,12 @@ class MemberParselet implements InfixParselet {
   int get precedence => 19;
 
   @override
-  Expression parse(Parser parser, Expression left, Token token) {
+  Expression? parse(Parser parser, Expression? left, Token? token) {
     var name = parser.parseIdentifier();
 
     if (name == null) {
       parser.errors.add(JaelError(JaelErrorSeverity.error,
-          'Expected the name of a property following "."', token.span));
+          'Expected the name of a property following "."', token!.span));
       return null;
     }
 
diff --git a/packages/jael/jael/lib/src/text/parselet/parselet.dart b/packages/jael/jael/lib/src/text/parselet/parselet.dart
index 2ff22119..72f9e9e9 100644
--- a/packages/jael/jael/lib/src/text/parselet/parselet.dart
+++ b/packages/jael/jael/lib/src/text/parselet/parselet.dart
@@ -6,10 +6,10 @@ part 'infix.dart';
 part 'prefix.dart';
 
 abstract class PrefixParselet {
-  Expression parse(Parser parser, Token token);
+  Expression? parse(Parser parser, Token? token);
 }
 
 abstract class InfixParselet {
   int get precedence;
-  Expression parse(Parser parser, Expression left, Token token);
+  Expression? parse(Parser parser, Expression? left, Token? token);
 }
diff --git a/packages/jael/jael/lib/src/text/parselet/prefix.dart b/packages/jael/jael/lib/src/text/parselet/prefix.dart
index cea9bb49..ada46bcc 100644
--- a/packages/jael/jael/lib/src/text/parselet/prefix.dart
+++ b/packages/jael/jael/lib/src/text/parselet/prefix.dart
@@ -16,12 +16,12 @@ class NotParselet implements PrefixParselet {
   const NotParselet();
 
   @override
-  Expression parse(Parser parser, Token token) {
+  Expression parse(Parser parser, Token? token) {
     var expression = parser.parseExpression(0);
 
     if (expression == null) {
       parser.errors.add(JaelError(JaelErrorSeverity.error,
-          'Missing expression after "!" in negation expression.', token.span));
+          'Missing expression after "!" in negation expression.', token!.span));
     }
 
     return Negation(token, expression);
@@ -32,14 +32,14 @@ class NewParselet implements PrefixParselet {
   const NewParselet();
 
   @override
-  Expression parse(Parser parser, Token token) {
+  Expression? parse(Parser parser, Token? token) {
     var call = parser.parseExpression(0);
 
     if (call == null) {
       parser.errors.add(JaelError(
           JaelErrorSeverity.error,
           '"new" must precede a call expression. Nothing was found.',
-          call.span));
+          call!.span));
       return null;
     } else if (call is Call) {
       return NewExpression(token, call);
@@ -57,31 +57,31 @@ class NumberParselet implements PrefixParselet {
   const NumberParselet();
 
   @override
-  Expression parse(Parser parser, Token token) => NumberLiteral(token);
+  Expression parse(Parser parser, Token? token) => NumberLiteral(token);
 }
 
 class HexParselet implements PrefixParselet {
   const HexParselet();
 
   @override
-  Expression parse(Parser parser, Token token) => HexLiteral(token);
+  Expression parse(Parser parser, Token? token) => HexLiteral(token);
 }
 
 class StringParselet implements PrefixParselet {
   const StringParselet();
 
   @override
-  Expression parse(Parser parser, Token token) =>
-      StringLiteral(token, StringLiteral.parseValue(token));
+  Expression parse(Parser parser, Token? token) =>
+      StringLiteral(token, StringLiteral.parseValue(token!));
 }
 
 class ArrayParselet implements PrefixParselet {
   const ArrayParselet();
 
   @override
-  Expression parse(Parser parser, Token token) {
+  Expression? parse(Parser parser, Token? token) {
     List<Expression> items = [];
-    Expression item = parser.parseExpression(0);
+    Expression? item = parser.parseExpression(0);
 
     while (item != null) {
       items.add(item);
@@ -92,7 +92,7 @@ class ArrayParselet implements PrefixParselet {
 
     if (!parser.next(TokenType.rBracket)) {
       var lastSpan = items.isEmpty ? null : items.last.span;
-      lastSpan ??= token.span;
+      lastSpan ??= token!.span;
       parser.errors.add(JaelError(JaelErrorSeverity.error,
           'Missing "]" to terminate array literal.', lastSpan));
       return null;
@@ -106,7 +106,7 @@ class MapParselet implements PrefixParselet {
   const MapParselet();
 
   @override
-  Expression parse(Parser parser, Token token) {
+  Expression? parse(Parser parser, Token? token) {
     var pairs = <KeyValuePair>[];
     var pair = parser.parseKeyValuePair();
 
@@ -118,7 +118,7 @@ class MapParselet implements PrefixParselet {
     }
 
     if (!parser.next(TokenType.rCurly)) {
-      var lastSpan = pairs.isEmpty ? token.span : pairs.last.span;
+      var lastSpan = pairs.isEmpty ? token!.span : pairs.last.span;
       parser.errors.add(JaelError(
           JaelErrorSeverity.error, 'Missing "}" in map literal.', lastSpan));
       return null;
@@ -132,19 +132,19 @@ class IdentifierParselet implements PrefixParselet {
   const IdentifierParselet();
 
   @override
-  Expression parse(Parser parser, Token token) => Identifier(token);
+  Expression parse(Parser parser, Token? token) => Identifier(token);
 }
 
 class ParenthesisParselet implements PrefixParselet {
   const ParenthesisParselet();
 
   @override
-  Expression parse(Parser parser, Token token) {
+  Expression? parse(Parser parser, Token? token) {
     var expression = parser.parseExpression(0);
 
     if (expression == null) {
       parser.errors.add(JaelError(JaelErrorSeverity.error,
-          'Missing expression after "(".', token.span));
+          'Missing expression after "(".', token!.span));
       return null;
     }
 
diff --git a/packages/jael/jael/lib/src/text/parser.dart b/packages/jael/jael/lib/src/text/parser.dart
index 9225726f..c3c26b9e 100644
--- a/packages/jael/jael/lib/src/text/parser.dart
+++ b/packages/jael/jael/lib/src/text/parser.dart
@@ -7,12 +7,12 @@ class Parser {
   final Scanner scanner;
   final bool asDSX;
 
-  Token _current;
+  Token? _current;
   int _index = -1;
 
   Parser(this.scanner, {this.asDSX = false});
 
-  Token get current => _current;
+  Token? get current => _current;
 
   int _nextPrecedence() {
     var tok = peek();
@@ -33,12 +33,12 @@ class Parser {
     return true;
   }
 
-  Token peek() {
+  Token? peek() {
     if (_index >= scanner.tokens.length - 1) return null;
     return scanner.tokens[_index + 1];
   }
 
-  Token maybe(TokenType type) => next(type) ? _current : null;
+  Token? maybe(TokenType type) => next(type) ? _current : null;
 
   void skipExtraneous(TokenType type) {
     while (next(type)) {
@@ -46,7 +46,7 @@ class Parser {
     }
   }
 
-  Document parseDocument() {
+  Document? parseDocument() {
     var doctype = parseDoctype();
 
     if (doctype == null) {
@@ -66,10 +66,10 @@ class Parser {
     return Document(doctype, root);
   }
 
-  StringLiteral implicitString() {
+  StringLiteral? implicitString() {
     if (next(TokenType.string)) {
-      return prefixParselets[TokenType.string].parse(this, _current)
-          as StringLiteral;
+      return prefixParselets[TokenType.string]!.parse(this, _current)
+          as StringLiteral?;
     }
     /*else if (next(TokenType.text)) {
 
@@ -78,7 +78,7 @@ class Parser {
     return null;
   }
 
-  Doctype parseDoctype() {
+  Doctype? parseDoctype() {
     if (!next(TokenType.lt)) return null;
     var lt = _current;
 
@@ -86,12 +86,12 @@ class Parser {
       _index--;
       return null;
     }
-    var doctype = _current, html = parseIdentifier();
-    if (html?.span?.text?.toLowerCase() != 'html') {
+    var doctype = _current, html = parseIdentifier() as Token?;
+    if (html?.span?.text.toLowerCase() != 'html') {
       errors.add(JaelError(
           JaelErrorSeverity.error,
           'Expected "html" in doctype declaration.',
-          html?.span ?? doctype.span));
+          html?.span ?? doctype!.span));
       return null;
     }
 
@@ -99,18 +99,19 @@ class Parser {
     if (public == null) {
       if (!next(TokenType.gt)) {
         errors.add(JaelError(JaelErrorSeverity.error,
-            'Expected ">" in doctype declaration.', html.span));
+            'Expected ">" in doctype declaration.', html!.span));
         return null;
       }
 
-      return Doctype(lt, doctype, html, null, null, null, _current);
+      return Doctype(
+          lt, doctype, html as Identifier?, null, null, null, _current);
     }
 
-    if (public?.span?.text?.toLowerCase() != 'public') {
+    if (public.span?.text.toLowerCase() != 'public') {
       errors.add(JaelError(
           JaelErrorSeverity.error,
           'Expected "public" in doctype declaration.',
-          public?.span ?? html.span));
+          public.span ?? html!.span));
       return null;
     }
 
@@ -122,37 +123,38 @@ class Parser {
       return null;
     }
 
-    var name = stringParser.parse(this, _current) as StringLiteral;
+    var name = stringParser!.parse(this, _current) as StringLiteral?;
 
     if (!next(TokenType.string)) {
       errors.add(JaelError(JaelErrorSeverity.error,
-          'Expected string in doctype declaration.', name.span));
+          'Expected string in doctype declaration.', name!.span));
       return null;
     }
 
-    var url = stringParser.parse(this, _current) as StringLiteral;
+    var url = stringParser.parse(this, _current) as StringLiteral?;
 
     if (!next(TokenType.gt)) {
       errors.add(JaelError(JaelErrorSeverity.error,
-          'Expected ">" in doctype declaration.', url.span));
+          'Expected ">" in doctype declaration.', url!.span));
       return null;
     }
 
-    return Doctype(lt, doctype, html, public, name, url, _current);
+    return Doctype(
+        lt, doctype, html as Identifier?, public, name, url, _current);
   }
 
-  ElementChild parseElementChild() =>
+  ElementChild? parseElementChild() =>
       parseHtmlComment() ??
       parseInterpolation() ??
       parseText() ??
       parseElement();
 
-  HtmlComment parseHtmlComment() =>
+  HtmlComment? parseHtmlComment() =>
       next(TokenType.htmlComment) ? HtmlComment(_current) : null;
 
-  Text parseText() => next(TokenType.text) ? Text(_current) : null;
+  Text? parseText() => next(TokenType.text) ? Text(_current) : null;
 
-  Interpolation parseInterpolation() {
+  Interpolation? parseInterpolation() {
     if (!next(asDSX ? TokenType.lCurly : TokenType.lDoubleCurly)) return null;
     var doubleCurlyL = _current;
 
@@ -160,7 +162,7 @@ class Parser {
 
     if (expression == null) {
       errors.add(JaelError(JaelErrorSeverity.error,
-          'Missing expression in interpolation.', doubleCurlyL.span));
+          'Missing expression in interpolation.', doubleCurlyL!.span));
       return null;
     }
 
@@ -174,7 +176,7 @@ class Parser {
     return Interpolation(doubleCurlyL, expression, _current);
   }
 
-  Element parseElement() {
+  Element? parseElement() {
     if (!next(TokenType.lt)) return null;
     var lt = _current;
 
@@ -188,11 +190,11 @@ class Parser {
 
     if (tagName == null) {
       errors.add(
-          JaelError(JaelErrorSeverity.error, 'Missing tag name.', lt.span));
+          JaelError(JaelErrorSeverity.error, 'Missing tag name.', lt!.span));
       return null;
     }
 
-    List<Attribute> attributes = [];
+    var attributes = <Attribute>[];
     var attribute = parseAttribute();
 
     while (attribute != null) {
@@ -206,7 +208,7 @@ class Parser {
 
       if (!next(TokenType.gt)) {
         errors.add(JaelError(JaelErrorSeverity.error,
-            'Missing ">" in self-closing "${tagName.name}" tag.', slash.span));
+            'Missing ">" in self-closing "${tagName.name}" tag.', slash!.span));
         return null;
       }
 
@@ -228,7 +230,7 @@ class Parser {
       return SelfClosingElement(lt, tagName, attributes, null, gt);
     }
 
-    List<ElementChild> children = [];
+    var children = <ElementChild>[];
     var child = parseElementChild();
 
     while (child != null) {
@@ -250,25 +252,26 @@ class Parser {
 
     if (!next(TokenType.slash)) {
       errors.add(JaelError(JaelErrorSeverity.error,
-          'Missing "/" in "${tagName.name}" closing tag.', lt2.span));
+          'Missing "/" in "${tagName.name}" closing tag.', lt2!.span));
       return null;
     }
 
-    var slash = _current, tagName2 = parseIdentifier();
+    var slash = _current;
+    var tagName2 = parseIdentifier();
 
     if (tagName2 == null) {
       errors.add(JaelError(
           JaelErrorSeverity.error,
           'Missing "${tagName.name}" in "${tagName.name}" closing tag.',
-          slash.span));
+          slash!.span));
       return null;
     }
 
     if (tagName2.name != tagName.name) {
       errors.add(JaelError(
           JaelErrorSeverity.error,
-          'Mismatched closing tags. Expected "${tagName.span.text}"; got "${tagName2.name}" instead.',
-          lt2.span));
+          'Mismatched closing tags. Expected "${tagName.span!.text}"; got "${tagName2.name}" instead.',
+          lt2!.span));
       return null;
     }
 
@@ -282,19 +285,19 @@ class Parser {
         lt, tagName, attributes, gt, children, lt2, slash, tagName2, _current);
   }
 
-  Attribute parseAttribute() {
-    Identifier id;
-    StringLiteral string;
+  Attribute? parseAttribute() {
+    Identifier? id;
+    StringLiteral? string;
 
     if ((id = parseIdentifier()) != null) {
       // Nothing
     } else if (next(TokenType.string)) {
-      string = StringLiteral(_current, StringLiteral.parseValue(_current));
+      string = StringLiteral(_current, StringLiteral.parseValue(_current!));
     } else {
       return null;
     }
 
-    Token equals, nequ;
+    Token? equals, nequ;
 
     if (next(TokenType.equals)) {
       equals = _current;
@@ -309,7 +312,7 @@ class Parser {
 
       if (value == null) {
         errors.add(JaelError(JaelErrorSeverity.error,
-            'Missing expression in attribute.', equals?.span ?? nequ.span));
+            'Missing expression in attribute.', equals?.span ?? nequ!.span));
         return null;
       }
 
@@ -329,22 +332,22 @@ class Parser {
       }
 
       errors.add(JaelError(JaelErrorSeverity.error,
-          'Missing expression in attribute.', equals?.span ?? nequ.span));
+          'Missing expression in attribute.', equals?.span ?? nequ!.span));
       return null;
     }
   }
 
-  Expression parseExpression(int precedence) {
+  Expression? parseExpression(int precedence) {
     // Only consume a token if it could potentially be a prefix parselet
 
     for (var type in prefixParselets.keys) {
       if (next(type)) {
-        var left = prefixParselets[type].parse(this, _current);
+        var left = prefixParselets[type]!.parse(this, _current);
 
         while (precedence < _nextPrecedence()) {
           _current = scanner.tokens[++_index];
 
-          if (_current.type == TokenType.slash &&
+          if (_current!.type == TokenType.slash &&
               peek()?.type == TokenType.gt) {
             // Handle `/>`
             //
@@ -354,11 +357,11 @@ class Parser {
             return left;
           }
 
-          var infix = infixParselets[_current.type];
+          var infix = infixParselets[_current!.type]!;
           var newLeft = infix.parse(this, left, _current);
 
           if (newLeft == null) {
-            if (_current.type == TokenType.gt) _index--;
+            if (_current!.type == TokenType.gt) _index--;
             return left;
           }
           left = newLeft;
@@ -372,27 +375,27 @@ class Parser {
     return null;
   }
 
-  Identifier parseIdentifier() =>
+  Identifier? parseIdentifier() =>
       next(TokenType.id) ? Identifier(_current) : null;
 
-  KeyValuePair parseKeyValuePair() {
+  KeyValuePair? parseKeyValuePair() {
     var key = parseExpression(0);
     if (key == null) return null;
 
     if (!next(TokenType.colon)) return KeyValuePair(key, null, null);
 
-    var colon = _current, value = parseExpression(0);
+    var colon = _current, value = parseExpression(0) as Token?;
 
     if (value == null) {
       errors.add(JaelError(JaelErrorSeverity.error,
-          'Missing expression in key-value pair.', colon.span));
+          'Missing expression in key-value pair.', colon!.span));
       return null;
     }
 
-    return KeyValuePair(key, colon, value);
+    return KeyValuePair(key, colon, value as Expression?);
   }
 
-  NamedArgument parseNamedArgument() {
+  NamedArgument? parseNamedArgument() {
     var name = parseIdentifier();
     if (name == null) return null;
 
@@ -402,14 +405,14 @@ class Parser {
       return null;
     }
 
-    var colon = _current, value = parseExpression(0);
+    var colon = _current, value = parseExpression(0) as Token?;
 
     if (value == null) {
       errors.add(JaelError(JaelErrorSeverity.error,
-          'Missing expression in named argument.', colon.span));
+          'Missing expression in named argument.', colon!.span));
       return null;
     }
 
-    return NamedArgument(name, colon, value);
+    return NamedArgument(name, colon, value as Expression);
   }
 }
diff --git a/packages/jael/jael/lib/src/text/scanner.dart b/packages/jael/jael/lib/src/text/scanner.dart
index 964368ae..24f26e3d 100644
--- a/packages/jael/jael/lib/src/text/scanner.dart
+++ b/packages/jael/jael/lib/src/text/scanner.dart
@@ -85,44 +85,44 @@ class _Scanner implements Scanner {
   final List<JaelError> errors = [];
   final List<Token> tokens = [];
   _ScannerState state = _ScannerState.html;
-  final Queue<String> openTags = Queue();
+  final Queue<String?> openTags = Queue();
 
-  SpanScanner _scanner;
+  SpanScanner? _scanner;
 
   _Scanner(String text, sourceUrl) {
     _scanner = SpanScanner(text, sourceUrl: sourceUrl);
   }
 
   void scan({bool asDSX = false}) {
-    while (!_scanner.isDone) {
+    while (!_scanner!.isDone) {
       if (state == _ScannerState.html) {
         scanHtml(asDSX);
       } else if (state == _ScannerState.freeText) {
         // Just keep parsing until we hit "</"
-        var start = _scanner.state, end = start;
+        var start = _scanner!.state, end = start;
 
-        while (!_scanner.isDone) {
+        while (!_scanner!.isDone) {
           // Skip through comments
-          if (_scanner.scan(_htmlComment)) continue;
+          if (_scanner!.scan(_htmlComment)) continue;
 
           // Break on {{ or {
-          if (_scanner.matches(asDSX ? '{' : '{{')) {
+          if (_scanner!.matches(asDSX ? '{' : '{{')) {
             state = _ScannerState.html;
             //_scanner.position--;
             break;
           }
 
-          var ch = _scanner.readChar();
+          var ch = _scanner!.readChar();
 
           if (ch == $lt) {
             // && !_scanner.isDone) {
-            if (_scanner.matches('/')) {
+            if (_scanner!.matches('/')) {
               // If we reached "</", backtrack and break into HTML
               openTags.removeFirst();
-              _scanner.position--;
+              _scanner!.position--;
               state = _ScannerState.html;
               break;
-            } else if (_scanner.matches(_id)) {
+            } else if (_scanner!.matches(_id)) {
               // Also break when we reach <foo.
               //
               // HOWEVER, that is also JavaScript. So we must
@@ -132,26 +132,26 @@ class _Scanner implements Scanner {
 
               if (!shouldBreak) {
                 // Try to see if we are closing a script tag
-                var replay = _scanner.state;
+                var replay = _scanner!.state;
                 _scanner
-                  ..readChar()
+                  ?..readChar()
                   ..scan(_whitespace);
                 //print(_scanner.emptySpan.highlight());
 
-                if (_scanner.matches(_id)) {
+                if (_scanner!.matches(_id)) {
                   //print(_scanner.lastMatch[0]);
-                  shouldBreak = _scanner.lastMatch[0] == 'script';
-                  _scanner.position--;
+                  shouldBreak = _scanner!.lastMatch![0] == 'script';
+                  _scanner!.position--;
                 }
 
                 if (!shouldBreak) {
-                  _scanner.state = replay;
+                  _scanner!.state = replay;
                 }
               }
 
               if (shouldBreak) {
                 openTags.removeFirst();
-                _scanner.position--;
+                _scanner!.position--;
                 state = _ScannerState.html;
                 break;
               }
@@ -159,10 +159,10 @@ class _Scanner implements Scanner {
           }
 
           // Otherwise, just add to the "buffer"
-          end = _scanner.state;
+          end = _scanner!.state;
         }
 
-        var span = _scanner.spanFrom(start, end);
+        var span = _scanner!.spanFrom(start, end);
 
         if (span.text.isNotEmpty) {
           tokens.add(Token(TokenType.text, span, null));
@@ -182,34 +182,35 @@ class _Scanner implements Scanner {
 
         while (true) {
           // Scan whitespace
-          _scanner.scan(_whitespace);
+          _scanner!.scan(_whitespace);
 
           _expressionPatterns.forEach((pattern, type) {
-            if (_scanner.matches(pattern)) {
-              potential.add(Token(type, _scanner.lastSpan, _scanner.lastMatch));
+            if (_scanner!.matches(pattern)) {
+              potential
+                  .add(Token(type, _scanner!.lastSpan, _scanner!.lastMatch));
             }
           });
 
-          potential.sort((a, b) => b.span.length.compareTo(a.span.length));
+          potential.sort((a, b) => b.span!.length.compareTo(a.span!.length));
 
           if (potential.isEmpty) break;
 
           var token = potential.first;
           tokens.add(token);
 
-          _scanner.scan(token.span.text);
+          _scanner!.scan(token.span!.text);
 
           if (token.type == TokenType.lt) {
             brackets.addFirst(token);
 
             // Try to see if we are at a tag.
-            var replay = _scanner.state;
-            _scanner.scan(_whitespace);
+            var replay = _scanner!.state;
+            _scanner!.scan(_whitespace);
 
-            if (_scanner.matches(_id)) {
-              openTags.addFirst(_scanner.lastMatch[0]);
+            if (_scanner!.matches(_id)) {
+              openTags.addFirst(_scanner!.lastMatch![0]);
             } else {
-              _scanner.state = replay;
+              _scanner!.state = replay;
             }
           } else if (token.type == TokenType.slash) {
             // Only push if we're at </foo
@@ -225,11 +226,11 @@ class _Scanner implements Scanner {
               brackets.removeFirst();
 
               // Now, ONLY continue parsing HTML if the next character is '<'.
-              var replay = _scanner.state;
-              _scanner.scan(_whitespace);
+              var replay = _scanner!.state;
+              _scanner!.scan(_whitespace);
 
-              if (!_scanner.matches('<')) {
-                _scanner.state = replay;
+              if (!_scanner!.matches('<')) {
+                _scanner!.state = replay;
                 state = _ScannerState.freeText;
                 break;
               }
@@ -240,11 +241,11 @@ class _Scanner implements Scanner {
               // We're at foo>, try to parse text?
               brackets.removeFirst();
 
-              var replay = _scanner.state;
-              _scanner.scan(_whitespace);
+              var replay = _scanner!.state;
+              _scanner!.scan(_whitespace);
 
-              if (!_scanner.matches('<')) {
-                _scanner.state = replay;
+              if (!_scanner!.matches('<')) {
+                _scanner!.state = replay;
                 state = _ScannerState.freeText;
                 break;
               }
@@ -258,7 +259,7 @@ class _Scanner implements Scanner {
           potential.clear();
         }
       }
-    } while (brackets.isNotEmpty && !_scanner.isDone);
+    } while (brackets.isNotEmpty && !_scanner!.isDone);
 
     state = _ScannerState.freeText;
   }
diff --git a/packages/jael/jael/pubspec.yaml b/packages/jael/jael/pubspec.yaml
index 3fcb164e..3b2f9fda 100644
--- a/packages/jael/jael/pubspec.yaml
+++ b/packages/jael/jael/pubspec.yaml
@@ -3,15 +3,25 @@ version: 3.0.0
 description:  A simple server-side HTML templating engine for Dart. Comparable to Blade or Liquid.
 author: Tobe O <thosakwe@gmail.com>
 homepage: https://docs.angel-dart.dev/packages/front-end/jael
+publish_to: none
 environment:
-  sdk: '>=2.10.0 <3.0.0'
+  sdk: '>=2.12.0 <3.0.0'
 dependencies:
   args: ^2.0.0
   charcode: ^1.0.0
-  code_buffer: ^1.0.0
+  code_buffer:
+    git: 
+      url: https://github.com/dukefirehawk/angel.git
+      ref: sdk-2.12.x_nnbd
+      path: packages/code_buffer
   source_span: ^1.0.0
   string_scanner: ^1.0.0
-  symbol_table: ^2.0.0
+  symbol_table:
+    git: 
+      url: https://github.com/dukefirehawk/angel.git
+      ref: sdk-2.12.x_nnbd
+      path: packages/symbol_table
+  collection: ^1.15.0-nullsafety.4  
 dev_dependencies:
   pedantic: ^1.0.0
   test: ^1.0.0
diff --git a/packages/jael/jael/test/render/custom_element_test.dart b/packages/jael/jael/test/render/custom_element_test.dart
index 303c1627..489d506b 100644
--- a/packages/jael/jael/test/render/custom_element_test.dart
+++ b/packages/jael/jael/test/render/custom_element_test.dart
@@ -105,8 +105,8 @@ void main() {
   });
 }
 
-String render(String template, [Map<String, dynamic> values]) {
-  var doc = jael.parseDocument(template, onError: (e) => throw e);
+String render(String template, [Map<String, dynamic> values = const {}]) {
+  var doc = jael.parseDocument(template, onError: (e) => throw e)!;
   var buffer = CodeBuffer();
   const jael.Renderer().render(doc, buffer, SymbolTable(values: values));
   return buffer.toString();
diff --git a/packages/jael/jael/test/render/dsx_test.dart b/packages/jael/jael/test/render/dsx_test.dart
index 8c47ed7f..607e3deb 100644
--- a/packages/jael/jael/test/render/dsx_test.dart
+++ b/packages/jael/jael/test/render/dsx_test.dart
@@ -6,18 +6,18 @@ void main() {
   test('attributes', () {
     var doc = parseDSX('''
     <foo bar="baz" yes={no} />
-    ''');
+    ''')!;
 
     var foo = doc.root as SelfClosingElement;
     expect(foo.tagName.name, 'foo');
     expect(foo.attributes, hasLength(2));
     expect(foo.getAttribute('bar'), isNotNull);
     expect(foo.getAttribute('yes'), isNotNull);
-    expect(foo.getAttribute('bar').value.compute(null), 'baz');
+    expect(foo.getAttribute('bar')?.value?.compute(null), 'baz');
     expect(
         foo
-            .getAttribute('yes')
-            .value
+            .getAttribute('yes')!
+            .value!
             .compute(SymbolTable(values: {'no': 'maybe'})),
         'maybe');
   });
@@ -27,7 +27,7 @@ void main() {
     <foo bar="baz" yes={no}>
       <bar>{24 * 3}</bar>
     </foo>
-    ''');
+    ''')!;
 
     var bar = doc.root.children.first as RegularElement;
     expect(bar.tagName.name, 'bar');
@@ -37,7 +37,7 @@ void main() {
   });
 }
 
-Document parseDSX(String text) {
+Document? parseDSX(String text) {
   return parseDocument(text,
       sourceUrl: 'test.dsx', asDSX: true, onError: (e) => throw e);
 }
diff --git a/packages/jael/jael/test/render/render_test.dart b/packages/jael/jael/test/render/render_test.dart
index b9a60e07..504a9c2f 100644
--- a/packages/jael/jael/test/render/render_test.dart
+++ b/packages/jael/jael/test/render/render_test.dart
@@ -16,8 +16,8 @@ main() {
 ''';
 
     var buf = CodeBuffer();
-    jael.Document document;
-    SymbolTable scope;
+    jael.Document? document;
+    late SymbolTable scope;
 
     try {
       document = jael.parseDocument(template, sourceUrl: 'test.jael');
@@ -33,7 +33,7 @@ main() {
     }
 
     expect(document, isNotNull);
-    const jael.Renderer().render(document, buf, scope);
+    const jael.Renderer().render(document!, buf, scope);
     print(buf);
 
     expect(
@@ -66,7 +66,7 @@ main() {
 
     var buf = CodeBuffer();
     //jael.scan(template, sourceUrl: 'test.jael').tokens.forEach(print);
-    var document = jael.parseDocument(template, sourceUrl: 'test.jael');
+    var document = jael.parseDocument(template, sourceUrl: 'test.jael')!;
     var scope = SymbolTable<dynamic>(values: {
       'pokemon': const _Pokemon('Darkrai', 'Dark'),
     });
@@ -106,7 +106,7 @@ main() {
 ''';
 
     var buf = CodeBuffer();
-    var document = jael.parseDocument(template, sourceUrl: 'test.jael');
+    var document = jael.parseDocument(template, sourceUrl: 'test.jael')!;
     var scope = SymbolTable<dynamic>(values: {
       'starters': starters,
     });
@@ -151,7 +151,7 @@ main() {
 ''';
 
     var buf = CodeBuffer();
-    var document = jael.parseDocument(template, sourceUrl: 'test.jael');
+    var document = jael.parseDocument(template, sourceUrl: 'test.jael')!;
     var scope = SymbolTable<dynamic>(values: {
       'starters': starters,
     });
@@ -197,7 +197,7 @@ main() {
 ''';
 
     var buf = CodeBuffer();
-    var document = jael.parseDocument(template, sourceUrl: 'test.jael');
+    var document = jael.parseDocument(template, sourceUrl: 'test.jael')!;
     var scope = SymbolTable();
 
     const jael.Renderer().render(document, buf, scope);
@@ -243,7 +243,7 @@ main() {
 ''';
 
     var buf = CodeBuffer();
-    var document = jael.parseDocument(template, sourceUrl: 'test.jael');
+    var document = jael.parseDocument(template, sourceUrl: 'test.jael')!;
     var scope = SymbolTable();
 
     const jael.Renderer().render(document, buf, scope);
@@ -268,7 +268,7 @@ main() {
 ''';
 
     var buf = CodeBuffer();
-    var document = jael.parseDocument(template, sourceUrl: 'test.jael');
+    var document = jael.parseDocument(template, sourceUrl: 'test.jael')!;
     var scope = SymbolTable();
 
     const jael.Renderer().render(document, buf, scope);
@@ -299,7 +299,7 @@ main() {
 ''';
 
     var buf = CodeBuffer();
-    var document = jael.parseDocument(template, sourceUrl: 'test.jael');
+    var document = jael.parseDocument(template, sourceUrl: 'test.jael')!;
     var scope = SymbolTable<dynamic>(values: {
       'account': _Account(isDisabled: true),
     });
@@ -326,7 +326,7 @@ main() {
 ''';
 
     var buf = CodeBuffer();
-    var document = jael.parseDocument(template, sourceUrl: 'test.jael');
+    var document = jael.parseDocument(template, sourceUrl: 'test.jael')!;
     var scope = SymbolTable<dynamic>(values: {
       'account': _Account(isDisabled: null),
     });
@@ -351,7 +351,7 @@ class _Pokemon {
 }
 
 class _Account {
-  final bool isDisabled;
+  final bool? isDisabled;
 
   _Account({this.isDisabled});
 }
diff --git a/packages/jael/jael/test/text/common.dart b/packages/jael/jael/test/text/common.dart
index 5fb71587..fa17e560 100644
--- a/packages/jael/jael/test/text/common.dart
+++ b/packages/jael/jael/test/text/common.dart
@@ -1,11 +1,11 @@
 import 'package:matcher/matcher.dart';
 import 'package:jael/src/ast/token.dart';
 
-Matcher isToken(TokenType type, [String text]) => _IsToken(type, text);
+Matcher isToken(TokenType type, [String? text]) => _IsToken(type, text);
 
 class _IsToken extends Matcher {
   final TokenType type;
-  final String text;
+  final String? text;
 
   _IsToken(this.type, [this.text]);
 
@@ -19,6 +19,6 @@ class _IsToken extends Matcher {
   bool matches(item, Map matchState) {
     return item is Token &&
         item.type == type &&
-        (text == null || item.span.text == text);
+        (text == null || item.span!.text == text);
   }
 }
diff --git a/packages/symbol_table/pubspec.yaml b/packages/symbol_table/pubspec.yaml
index 0c605c46..db526ea4 100644
--- a/packages/symbol_table/pubspec.yaml
+++ b/packages/symbol_table/pubspec.yaml
@@ -1,8 +1,9 @@
 name: symbol_table
-version: 2.0.0
+version: 3.0.0
 description: A generic symbol table implementation in Dart, with support for scopes and constants.
 author: Tobe O <thosakwe@gmail.com>
 homepage: https://github.com/thosakwe/symbol_table
+publish_to: none
 environment:
   sdk: '>=2.12.0 <3.0.0'
 dependencies: