Fix crash for a dangling pointer

Task-Number: BAUHAUS-574
Reviewed-by: kkoehne
(cherry picked from commit 629a4d66c1)

src/plugins/qmldesigner/core/instances/nodeinstancemetaobject.cpp

@@ -62,10 +62,12 @@ int NodeInstanceMetaObject::metaCall(QMetaObject::Call call, int id, void **a)
             }
         }
     } else {
+        if (!QObjectPrivate::get(object())->wasDeleted) {
             if (parent())
                 metaCallReturnValue = parent()->metaCall(call, id, a);
             else
                 metaCallReturnValue = object()->qt_metacall(call, id, a);
+        }
 
         if (call == QMetaObject::WriteProperty
             && !property(id).hasNotifySignal()