generateJson not compatible with const constructors

[befora]

Example to recreate issue:

import 'package:morphy_annotation/morphy_annotation.dart';

part 'pet.g.dart';
part 'pet.morphy.dart';

@Morphy(generateJson: true)
abstract class $Pet {
  const $Pet();
  String get type;
}

I get this error:

Error: Non-constant map literal is not a constant expression.
  Map<Type, Object? Function(Never)> _fns = {}

[befora]

I removed these lines from the generated morphy.dart file and it solved the issue.

  // ignore: unused_field
  Map<Type, Object? Function(Never)> _fns = {};

  Map<String, dynamic> toJson_2([Map<Type, Object? Function(Never)>? fns]) {
    this._fns = fns ?? {};
    return toJson();
  }

[atreeon]

Thanks @befora, this is indeed a bug. It looks like the json functionality and the constant functionality don't work together. I'll fix this hopefully in a couple of weeks and batch some other changes up.

As a workaround you can either set the generate json to false @morphy(generateJson: false)
or you can make the class a non constant.

Perhaps it might be a rarity to have a constant that you serialize anyway as the constant value would be known at compile time??? I may be missing an edge case though and will fix it regardless.

[morphy]

I'm starting to think that I should have checked this nickname before creating an account, I'm getting tagged in this project at least once a month ;P