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

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

Possible null reference assignment.

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

Cannot convert null literal to non-nullable reference type.

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

Cannot convert null literal to non-nullable reference type.

Nullability of reference types in type of parameter 'sender' of 'void AudioOutputForm.DropDownOnSelectedChange(object sender, EventArgs e)' doesn't match the target delegate 'EventHandler' (possibly because of nullability attributes).

Dereference of a possibly null reference.