catch case that users tries to delete all items in the dialog list

src/Mod/PartDesign/Gui/TaskDraftParameters.cpp

@@ -28,6 +28,7 @@
 # include <QMessageBox>
 # include <QAction>
 # include <QListWidget>
+# include <QMessageBox>
 #endif
 
 #include "ui_TaskDraftParameters.h"
@@ -243,6 +244,12 @@ void TaskDraftParameters::onRefDeleted(void)
     // get the list of items to be deleted
     QList<QListWidgetItem*> selectedList = ui->listWidgetReferences->selectedItems();
 
+    // if all items are selected, we must stop because one must be kept to avoid that the feature gets broken
+    if (selectedList.count() == ui->listWidgetReferences->model()->rowCount()) {
+        QMessageBox::warning(this, tr("Selection error"), tr("At least one item must be kept."));
+        return;
+    }
+
     // delete the selection backwards to assure the list index keeps valid for the deletion
     for (int i = selectedList.count() - 1; i > -1; i--) {
         QListWidgetItem* item = selectedList.at(i);