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

Possible null reference assignment.

Cannot convert null literal to non-nullable reference type.

Cannot convert null literal to non-nullable reference type.

The variable 'e' is declared but never used

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

Nullability of reference types in type of parameter 'sender' of 'void Form1.Form1_Load(object sender, EventArgs e)' doesn't match the target delegate 'EventHandler' (possibly because of nullability attributes).

Nullability of reference types in type of parameter 'sender' of 'void Form1.Form1_FormClosing(object sender, FormClosingEventArgs e)' doesn't match the target delegate 'FormClosingEventHandler' (possibly because of nullability attributes).

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