toJson method Null safety

Implementation

Map<String, dynamic> toJson() {
  final Map<String, dynamic> data = <String, dynamic>{};
  data['color'] = _color;
  if (_dDark != null) {
    data['_dark'] = _dDark!.toJson();
  }
  data['fontWeight'] = _fontWeight;
  data['lineHeight'] = _lineHeight;
  return data;
}