private void Button_Click_2(object sender, RoutedEventArgs e)
{
if (!(ListView.SelectedItem is Problem problem))
{
return;
}
foreach (var t in _problems)
{
if (t.ProblemId != problem.ProblemId)
{
continue;
}
Connection.DeleteProblem(t.ProblemId);
_problems.Remove(t);
break;
}
}