Catch exception in wpf PrincipalPermission(SecurityAction.Demand, Role = "Admin")

[danielxu]

I am working on a wpf app on basic authentication set ups with different roles. Say, two rules like Admin and Staff. Admin can add/delete users, but Staff can't. Now If I login as Admin, I can add/delete users who can access the app, but if I login as the role Staff, if I do add/delete users operations, the application will crash. I know the problem is I only allow Admin to perform such actions. But any ideas on how to throw an exception so that the app won't crash. I post my code, any ideas? Thanks in advance.

[PrincipalPermission(SecurityAction.Demand, Role = "Admin")]
public partial class UserRegistrationView : Window, IView
{
    public UserRegistrationView()
    {

        InitializeComponent();
    }

    private void btnCancel_Click(object sender, RoutedEventArgs e)
    {
        this.Close();
    }

    private void btnUpdate_Click(object sender, RoutedEventArgs e)
    {
        this.Close();
    }

    public IViewModel ViewModel
    {
        get
        {
            return DataContext as IViewModel;
        }
        set
        {
            DataContext = value;
        }
    }
}