anchor.diff:            title: 'Breakfast',
             value: Meal.breakfast,
             groupValue: Provider.of<DiningDataProvider>(context).mealTime,
  -          onChanged: (Meal value) {
  +          onChanged: (Meal? value) =>
               setState(() {
                 Provider.of<DiningDataProvider>(context, listen: false).mealTime =
  -                  value;
  -            });
  -          },
  +                  value!;
  +            })
           ),
           LabeledRadio(
             title: 'Lunch',
             value: Meal.lunch,
             groupValue: Provider.of<DiningDataProvider>(context).mealTime,
  -          onChanged: (Meal value) {
  +          onChanged: (Meal? value) {
               setState(() {
                 Provider.of<DiningDataProvider>(context, listen: false).mealTime =
  -                  value;
  +                  value!;
               });
             },
           ),
  
positive.code: 
  class LabeledRadio extends StatelessWidget {
    final String? title;
    final Meal? value;
    final Meal? groupValue;
    final Function? onChanged;
  
    const LabeledRadio(
        {Key? key, this.title, this.value, this.groupValue, this.onChanged})
        : super(key: key);
  
    @override
  
negative.code:             materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
              value: value,
              groupValue: groupValue,
              onChanged: onChanged,
              activeColor: Theme.of(context).buttonColor,
            ),
            Container(
  