Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

Non-nullable property 'ScoringRules' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'Questions' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'User' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Non-nullable property 'Quiz' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.

Nullability of reference types in type of parameter 'state' of 'void QuizModeView.EndQuiz(object state)' doesn't match the target delegate 'TimerCallback' (possibly because of nullability attributes).

Non-nullable field '_user' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.

Non-nullable field '_userQuiz' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.