Cannot convert null literal to non-nullable reference type.

'SliderView.PreviewTextInput(object, TextCompositionEventArgs)' hides inherited member 'UIElement.PreviewTextInput'. Use the new keyword if hiding was intended.

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

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

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

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

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

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

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