Error Message

Unhandled Exception: Bad state: No element

Before Code

var val = _list.singleWhere(
            (obj) => obj?.id == _selectedVal);

💡Solution Code

add orElse: () => null

var val = _list.singleWhere(
            (obj) => obj?.id == _selectedVal,
            orElse: () => null);

cf

https://github.com/flutter/flutter/issues/47040