Corrected introspection of enum types

example_star_wars/lib/src/models/episode.dart

@@ -1,3 +1,7 @@
+import 'package:graphql_schema/graphql_schema.dart';
+
+@GraphQLDocumentation(
+    description: 'The episodes of the Star Wars original trilogy.')
 enum Episode {
   NEWHOPE,
   EMPIRE,

example_star_wars/lib/star_wars.dart

@@ -51,6 +51,9 @@ Future configureServer(Angel app) async {
       field(
         'hero',
         type: heroType,
+        arguments: [
+          new GraphQLFieldArgument('ep', episodeType),
+        ],
         resolve: (_, args) async {
           var allHeroes = [];
           var allDroids = await droidService.index() as Iterable;
@@ -94,18 +97,24 @@ Future configureServer(Angel app) async {
     'total_credits': 520,
   });
 
+  var lando = await humansService.create({
+    'name': 'Lando Calrissian',
+    'appears_in': ['EMPIRE', 'JEDI'],
+    'total_credits': 525430,
+  });
+
   var hanSolo = await humansService.create({
     'name': 'Han Solo',
     'appears_in': ['NEWHOPE', 'EMPIRE', 'JEDI'],
     'total_credits': 23,
-    'friends': [leia],
+    'friends': [leia, lando],
   });
 
   var luke = await humansService.create({
     'name': 'Luke Skywalker',
     'appears_in': ['NEWHOPE', 'EMPIRE', 'JEDI'],
     'total_credits': 682,
-    'friends': [leia, hanSolo],
+    'friends': [leia, hanSolo, lando],
   });
 }
 

graphql_server/lib/introspection.dart

@@ -207,7 +207,9 @@ GraphQLObjectType _createTypeType() {
       resolve: (type, _) {
         var t = type as GraphQLType;
 
-        if (t is GraphQLScalarType)
+        if (t is GraphQLEnumType)
+          return 'ENUM';
+        else if (t is GraphQLScalarType)
           return 'SCALAR';
         else if (t is GraphQLObjectType)
           return t.isInterface ? 'INTERFACE' : 'OBJECT';
@@ -215,8 +217,6 @@ GraphQLObjectType _createTypeType() {
           return 'LIST';
         else if (t is GraphQLNonNullableType)
           return 'NON_NULL';
-        else if (t is GraphQLEnumType)
-          return 'ENUM';
         else if (t is GraphQLUnionType)
           return 'UNION';
         else
@@ -376,8 +376,7 @@ GraphQLObjectType _reflectDirectiveType() {
 GraphQLObjectType _enumValueType;
 
 GraphQLObjectType _reflectEnumValueType() {
-  return _enumValueType ??
-      objectType(
+  return _enumValueType ??= objectType(
     '__EnumValue',
     fields: [
       field(