update basket sum after deleting all articles

src/gui/mainwindow.cpp

@@ -400,6 +400,8 @@ void MainWindow::onCancelAllArticlesButtonClicked([[maybe_unused]] bool checked)
         return;
 
     dynamic_cast<BasketModel*>(ui_.basketView->model())->cancelSale();
+
+    ui_.basketSumLabel->setText(marketplace_->getBasketSumAsString().c_str()); // Update basket sum
 }
 
 void MainWindow::onAboutQt() { QMessageBox::aboutQt(this); }