Migrated angel_http_exception to nnbd

packages/http_exception/lib/angel_http_exception.dart

@@ -15,13 +15,13 @@ class AngelHttpException implements Exception {
   final List<String> errors = [];
 
   /// The cause of this exception.
-  String message;
+  String? message;
 
   /// The [StackTrace] associated with this error.
-  StackTrace stackTrace;
+  StackTrace? stackTrace;
 
   /// An HTTP status code this exception will throw.
-  int statusCode;
+  int? statusCode;
 
   AngelHttpException(this.error,
       {this.message = '500 Internal Server Error',
@@ -52,7 +52,7 @@ class AngelHttpException implements Exception {
   factory AngelHttpException.fromMap(Map data) {
     return AngelHttpException(
       null,
-      statusCode: (data['status_code'] ?? data['statusCode']) as int,
+      statusCode: (data['status_code'] ?? data['statusCode']) as int?,
       message: data['message']?.toString(),
       errors: data['errors'] is Iterable
           ? ((data['errors'] as Iterable).map((x) => x.toString()).toList())

packages/http_exception/pubspec.yaml

@@ -1,9 +1,9 @@
 name: angel_http_exception
-version: 2.0.0
+version: 2.1.0
 description: Exception class that can be serialized to JSON and serialized to clients.
 #author: Tobe O <thosakwe@gmail.com>
 homepage: https://github.com/dukefirehawk/angel/packages/http_exception
 environment:
-  sdk: ">=2.10.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 dev_dependencies:
   pedantic: ^1.11.0