QQuickWidget crash when closing QMdiSubWindow

#include <QApplication>
#include <QMainWindow>
#include <QMdiArea>
#include <QMdiSubWindow>
#include <QQuickWidget>
#include <QDebug>
#include <QPointer>

class Panel;

class PanelQT : public QWidget
{
public:
    PanelQT(Panel *p) : panel(p) { }
    ~PanelQT() { qDebug() << "dtor PanelQT"; }

    void closeEvent(QCloseEvent *ev);

private:
    Panel *panel;
};

class Panel : public QObject
{
public:
    Panel() { widget = new PanelQT(this); }

    ~Panel()
    {
        qDebug() << "dtor Panel";
        delete widget;
    }

    QWidget *getWidget() const { return widget; }

private:
    QPointer<PanelQT> widget;
};

void PanelQT::closeEvent(QCloseEvent *ev)
{
    ev->accept();
    panel->deleteLater();
}

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    QMainWindow mw;
    QMdiArea *mdiArea = new QMdiArea;
    mdiArea->setOption(QMdiArea::DontMaximizeSubWindowOnActivation);
    mdiArea->setHorizontalScrollBarPolicy(Qt::ScrollBarAsNeeded);
    mdiArea->setVerticalScrollBarPolicy(Qt::ScrollBarAsNeeded);
    mw.setCentralWidget(mdiArea);

    Panel *panel = new Panel;
    panel->getWidget()->resize(500, 500);

    QQuickWidget *quickWidget = new QQuickWidget(panel->getWidget());  // crashes
    //QWidget *quickWidget = new QWidget(panel->getWidget());  // works
    quickWidget->setGeometry(10, 10, 400, 400);

    QMdiSubWindow *subwindow = mdiArea->addSubWindow(panel->getWidget());
    subwindow->resize(500, 500);
    subwindow->show();

    mw.show();

    return app.exec();
}