Doesn't cope with null value in nullable field

[Andersmholmgren]

I have a field declared in a Built class as

  @nullable
  Object get defaultValue;

and similarly in the corresponding builder

The generated serialization code for this field looks like

      'defaultValue',
      serializers.serialize(object.defaultValue,
          specifiedType: FullType.unspecified),

When this runs with a value for object.defaultValue of null it blows up with the following

    Bad state: No serializer for 'Null'.
    #0      BuiltJsonSerializers.serialize (package:built_json/src/built_json_serializers.dart:34:9)
    #1      _$PropertySerializer.serialize (package:vcore/src/model/model.g.dart:168:19)
    #2      BuiltJsonSerializers.serialize (package:built_json/src/built_json_serializers.dart:55:14)
    #3      BuiltSetSerializer.serialize.<anonymous closure> (package:built_json/src/built_set_serializer.dart:28:31)
    #4      MappedIterator.moveNext (dart:_internal/iterable.dart:393)
    #5      List.List.from (dart:core-patch/array_patch.dart:40)
    #6      Iterable.toList (dart:core/iterable.dart:341)
    #7      BuiltJsonSerializers.serialize (package:built_json/src/built_json_serializers.dart:56:14)
    #8      _$ValueClassSerializer.serialize (package:vcore/src/model/model.g.dart:243:19)
    #9      BuiltJsonSerializers.serialize (package:built_json/src/built_json_serializers.dart:38:42)
    #10     VCoreModelGenerator.generate.<generate_async_body> (package:vcore_generator/src/vcore_model_generator.dart:31:37)

[Andersmholmgren]

I don't see any special treatment of fields annotated as @nullable in the json serialization generator code

[davidmorgan]

Thanks. This is a regression, it used to work by accident but there was never explicit handling/tests. Will take a look ASAP. Related #6

[davidmorgan]

Pull request: #24

You're welcome to review, or I'll ask someone here to take a look if you prefer.