[Reg] Crash when calling QMainWindow:.tabifiedDockWidgets after QMainWindow::removeDockWidget

QDockWidget *QMainWindowTabBar::dockAt(int index) const
{
    QMainWindowTabBar *that = const_cast<QMainWindowTabBar *>(this);
    QMainWindowLayout* mlayout = qt_mainwindow_layout(mainWindow);
    QDockAreaLayoutInfo *info = mlayout->dockInfo(that);
    if (!info)
        return nullptr;
    const int itemIndex = info->tabIndexToListIndex(index);
    Q_ASSERT(itemIndex >= 0 && itemIndex < info->item_list.count());
    const QDockAreaLayoutItem &item = info->item_list.at(itemIndex);
    return item.widgetItem ? qobject_cast<QDockWidget *>(item.widgetItem->widget()) : nullptr;
}

#include <QApplication>
#include <QDockWidget>
#include <QHBoxLayout>
#include <QMainWindow>
#include <QPushButton>

int main(int argc, char* argv[])
{
    QApplication application(argc, argv);
    QMainWindow mainWindow;

    // set up the dock widgets
    QDockWidget* dockWidgetA = new QDockWidget(&mainWindow);
    QDockWidget* dockWidgetB = new QDockWidget(&mainWindow);
    {
        dockWidgetA->setWindowTitle("A");
        dockWidgetB->setWindowTitle("B");

        mainWindow.addDockWidget(Qt::RightDockWidgetArea, dockWidgetA, Qt::Vertical);
        mainWindow.addDockWidget(Qt::RightDockWidgetArea, dockWidgetB, Qt::Vertical);
        mainWindow.tabifyDockWidget(dockWidgetB, dockWidgetA);
    }

    // set up the test
    {
        QWidget* centralWidget = new QWidget(&mainWindow);
        QHBoxLayout* centralWidgetLayout = new QHBoxLayout(centralWidget);

        mainWindow.setCentralWidget(centralWidget);

        QPushButton* testButton = new QPushButton("Crash", centralWidget);
        centralWidgetLayout->addWidget(testButton);

        QObject::connect(testButton, &QPushButton::clicked, testButton, [&mainWindow, dockWidgetA, dockWidgetB] {
            // remove one of the dock widgets
            mainWindow.removeDockWidget(dockWidgetA);
#if 1
            // crash!
            mainWindow.tabifiedDockWidgets(dockWidgetB);
#else
            // activating the layout first ensures that the main window layout is properly updated
            mainWindow.layout()->activate();
            mainWindow.tabifiedDockWidgets(dockWidgetB);
#endif
            });
	}

    mainWindow.show();

    return application.exec();
}