ModelEditor: Minor cleanup

Replace a dummy local var with nullptr

Change-Id: Ieea27fe894b141233b657a056cf3954f96649b03
Reviewed-by: Jochen Becher <jochen_becher@gmx.de>
Reviewed-by: hjk <hjk@theqtcompany.com>

src/plugins/modeleditor/actionhandler.cpp

@@ -130,11 +130,10 @@ void ActionHandler::createActions()
     medit->addAction(deleteCommand, Core::Constants::G_EDIT_COPYPASTE);
     d->deleteAction = deleteCommand->action();
     d->selectAllAction = registerCommand(Core::Constants::SELECTALL, [this]() { selectAll(); })->action();
-    const std::function<void()> emptySlot;
-    registerCommand(Constants::ACTION_ADD_PACKAGE, emptySlot);
-    registerCommand(Constants::ACTION_ADD_COMPONENT, emptySlot);
-    registerCommand(Constants::ACTION_ADD_CLASS, emptySlot);
-    registerCommand(Constants::ACTION_ADD_CANVAS_DIAGRAM, emptySlot);
+    registerCommand(Constants::ACTION_ADD_PACKAGE, nullptr);
+    registerCommand(Constants::ACTION_ADD_COMPONENT, nullptr);
+    registerCommand(Constants::ACTION_ADD_CLASS, nullptr);
+    registerCommand(Constants::ACTION_ADD_CANVAS_DIAGRAM, nullptr);
 }
 
 void ActionHandler::createEditPropertiesShortcut(const Core::Id &shortcutId)