private void Button_Click(object sender, RoutedEventArgs e)
 {
     if (txtFName.Text != "" && txtLName.Text != "")
     {
         var passenger = _fService.CreateNewPersonBooking(txtFName.Text, txtLName.Text);
         if (passenger != null)
         {
             _grid.AddPassengerToList(passenger);
         }
         else
         {
             MainWindow.ErrorMsg("Fejl! passenger er null");
         }
     }
     else
     {
         MainWindow.ErrorMsg("Begge felter skal udfyldes!");
     }
 }