Expected 'disable' or 'restore'

Dereference of a possibly null reference.

Converting null literal or possible null value to non-nullable type.

Possible null reference argument for parameter 'a' in 'bool Key.operator !=(Key a, Key? b)'.

Non-nullable field '_menuBar' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable field '_title' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable property 'Data' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the property as nullable.

Possible null reference argument for parameter 'a' in 'bool Key.operator !=(Key a, Key? b)'.

Possible null reference argument for parameter 'a' in 'bool Key.operator !=(Key a, Key? b)'.