private void DisplayErrorDialog()
 {
     try
     {
         throw new System.Exception();
     }
     catch (System.Exception ex)
     {
         DialogService.DisplayError(ex);
     }
 }
 private void OnDisplayErrorCommandExecuted()
 {
     try
     {
         throw new NullReferenceException();
     }
     catch (Exception ex)
     {
         DialogService.DisplayError(ex);
     }
 }