[SEVERE] json_serializable:json_serializable on bin/yaml_converter.dart:

Bad state: Unexpected diagnostics:
/Users/godofredoc/flutter_checkouts/flutter/bin/cache/dart-sdk/lib/core/int.dart:122:18 - Operator declarations must be preceded by the keyword 'operator'.
/Users/godofredoc/flutter_checkouts/flutter/bin/cache/dart-sdk/lib/core/int.dart:122:16 - Methods must have an explicit list of parameters.
/Users/godofredoc/flutter_checkouts/flutter/bin/cache/dart-sdk/lib/core/int.dart:122:18 - A function body must be provided.
package:analyzer/dart/sdk/build_sdk_summary.dart 212:7   _Builder._parse
package:analyzer/dart/sdk/build_sdk_summary.dart 147:36  _Builder._addLibrary
package:analyzer/dart/sdk/build_sdk_summary.dart 143:9   _Builder._addLibrary
package:analyzer/dart/sdk/build_sdk_summary.dart 143:9   _Builder._addLibrary
package:analyzer/dart/sdk/build_sdk_summary.dart 143:9   _Builder._addLibrary
dart:core                                                List.forEach
package:analyzer/dart/sdk/build_sdk_summary.dart 101:20  _Builder.build
package:analyzer/dart/sdk/build_sdk_summary.dart 75:5    buildSdkSummary
package:build_resolvers/src/resolver.dart 389:36         _defaultSdkSummaryGenerator
package:build_resolvers/src/resolver.dart 327:11         AnalyzerResolvers._ensureInitialized.<fn>
package:build_resolvers/src/resolver.dart 334:5          AnalyzerResolvers.get
package:build                                            _DelayedResolver.isLibrary
package:source_gen/src/builder.dart 75:10                _Builder.build