chore(api): make GraphQLResponse errors non-nullable

Author: Travis Sheppard

packages/amplify_core/lib/src/types/api/graphql/graphql_response.dart

@@ -22,12 +22,12 @@ class GraphQLResponse<T> {
   /// This will be `null` if there are any GraphQL errors during execution.
   final T? data;
 
-  /// A list of errors from execution. If no errors, it will be `null`.
-  final List<GraphQLResponseError>? errors;
+  /// A list of errors from execution. If no errors, it will be an empty list.
+  final List<GraphQLResponseError> errors;
 
   const GraphQLResponse({
     this.data,
-    this.errors,
+    required this.errors,
   });
 
   static GraphQLResponse<String?> raw({
@@ -36,10 +36,10 @@ class GraphQLResponse<T> {
   }) {
     return GraphQLResponse(
       data: data,
-      errors: errors,
+      errors: errors ?? const [],
     );
   }
 
   /// Whether errors are present in the response.
-  bool get hasErrors => errors != null && errors!.isNotEmpty;
+  bool get hasErrors => errors.isNotEmpty;
 }

packages/api/amplify_api/lib/src/graphql/helpers/graphql_response_decoder.dart

@@ -127,12 +127,12 @@ class GraphQLResponseDecoder {
   }
 }
 
-List<GraphQLResponseError>? _deserializeGraphQLResponseErrors(
+List<GraphQLResponseError> _deserializeGraphQLResponseErrors(
   Map<String, dynamic>? response,
 ) {
   final errors = response?['errors'] as List?;
   if (errors == null || errors.isEmpty) {
-    return null;
+    return [];
   }
   return errors
       .cast<Map<String, dynamic>>()

packages/api/amplify_api/test/graphql_test.dart

@@ -198,7 +198,7 @@ void main() {
       final expected = json.encode(_expectedQuerySuccessResponseBody['data']);
 
       expect(res.data, equals(expected));
-      expect(res.errors, equals(null));
+      expect(res.errors, isEmpty);
     });
 
     test('Query returns proper response.data with dynamic type', () async {
@@ -222,7 +222,7 @@ void main() {
       final expected = json.encode(_expectedQuerySuccessResponseBody['data']);
 
       expect(res.data, equals(expected));
-      expect(res.errors, equals(null));
+      expect(res.errors, isEmpty);
     });
 
     test('Mutate returns proper response.data', () async {
@@ -245,7 +245,7 @@ void main() {
       final expected = json.encode(_expectedMutateSuccessResponseBody['data']);
 
       expect(res.data, equals(expected));
-      expect(res.errors, equals(null));
+      expect(res.errors, isEmpty);
     });
   });
   group('Model Helpers', () {
@@ -270,7 +270,7 @@ void main() {
       // response asserts
       expect(res.data, isA<Blog>());
       expect(res.data?.id, _modelQueryId);
-      expect(res.errors, equals(null));
+      expect(res.errors, isEmpty);
     });
   });
 
@@ -387,7 +387,7 @@ void main() {
       );
 
       expect(res.data, equals(null));
-      expect(res.errors?.single, equals(errorExpected));
+      expect(res.errors.single, equals(errorExpected));
     });
 
     test('request with custom auth mode and auth error', () async {
@@ -414,7 +414,7 @@ void main() {
       );
 
       expect(res.data, equals(null));
-      expect(res.errors?.single, equals(errorExpected));
+      expect(res.errors.single, equals(errorExpected));
     });
 
     test('canceled query request should never resolve', () async {