How to catch errors caused by non-valid return-values ?

[homerun4711]

Hello!

I have a question on how to catch errors if a return-value is not accessible. I am unsure which is a good way to make sure, that a correct value is returned and what to do, if that value is not available.

The function is used to fetch values from a QDialog, called on exec().

QSqlRecord SelectAddress::passRecord()
 {
    //check if something is selected
    if(tableView->selectionModel()->hasSelection())
    {
        QModelIndex index = tableView->currentIndex();
       if (index.isValid())
            {
                QSqlRecord record = modelCustomer->record(index.row());
                return record;
            }
   }
   else
   {
      QMessageBox::warning(0, QObject::tr("Selection error"),"No entry selected");
      //application crashes here, what should be returned?
   }

QSqlRecord SelectAddress::passRecord()
 {
    //check if something is selected
    if(tableView->selectionModel()->hasSelection())
    {
        QModelIndex index = tableView->currentIndex();
       if (index.isValid())
            {
                QSqlRecord record = modelCustomer->record(index.row());
                return record;
            }
   }
   else
   {
      QMessageBox::warning(0, QObject::tr("Selection error"),"No entry selected");
      //application crashes here, what should be returned?
   }

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A point into the right direction would be enough.

Kind regards,
HomeR