Видео ютуба по тегу Flutter - 'Initialvalue == Null || Controller == Null': Is Not True

Solving Flutter Error: 'initialValue == null || controller == null': is not true
Solving Flutter Error: 'initialValue == null || controller == null': is not true
FLUTTER ERROR || Failed assertion: 'initialValue == null || controller == null': is not true.
FLUTTER ERROR || Failed assertion: 'initialValue == null || controller == null': is not true.
Flutter - 'initialValue == null || controller == null': is not true. error
Flutter - 'initialValue == null || controller == null': is not true. error