QmlDesigner: reset state editor model when error occurs

Task-number: QDS-695
Change-Id: I1e2e454c31eb92e865ccec9f7d68c5142488ddf9
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/plugins/qmldesigner/components/stateseditor/stateseditormodel.cpp

@@ -185,6 +185,7 @@ void StatesEditorModel::renameState(int internalNodeId, const QString &newName)
                                                newName.isEmpty() ?
                                                    tr("The empty string as a name is reserved for the base state.") :
                                                    tr("Name already used in another state"));
+        reset();
     } else {
         m_statesEditorView->renameState(internalNodeId, newName);
     }