Deletes commas after nullable type in parameter list

[munificent]

With 1.3.1, if I format:

class JsonCodec {
  const JsonCodec({
      Object? reviver(Object? key, Object? value)?,
      Object? toEncodable(dynamic object)?})
      : _reviver = reviver,
        _toEncodable = toEncodable;
}

It tries to produce:

class JsonCodec {
  const JsonCodec(
      {Object? reviver(Object? key, Object? value)?
      Object? toEncodable(dynamic object)?})
      : _reviver = reviver,
        _toEncodable = toEncodable;
}

Note the missing comma after the first parameter.