Crash when using aliases of a property with a deleted QObject

const char qmldata[]= R"-(

import QtQuick 2.4
import QtQuick.Window 2.2

Window {
    id:win;
    visible: true;

    property var modelData2;
    property alias modelData: win.modelData2;

    Text { anchors.fill: parent; text:"Click here"; }

    MouseArea {
        anchors.fill: parent;
        onClicked: {
            modelData = _myObj.create();
            console.log(modelData2);
            modelData.del();
            console.log(modelData); // null, that's good
            console.log(modelData2); // TypeError?
            if (modelData2) {
                echo ("index" in modelData2) // CRASH!
            }
       }
    }

}

)-";

#include <QApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>

class MyObj : public QObject {
    Q_OBJECT
public slots:
    QObject* create() { return (new MyObj); }
    void del() { delete this; }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("_myObj", new MyObj);
    engine.loadData(qmldata);
    return app.exec();
}


#include "main.moc"

==13626== Invalid read of size 8
==13626==    at 0x5FFF578: QV4::QObjectWrapper::findProperty(QV4::ExecutionEngine*, QQmlContextData*, QV4::String*, QV4::QObjectWrapper::RevisionMode, QQmlPropertyData*) const 
==13626==    by 0x5FFF8C1: QV4::QObjectWrapper::query(QV4::Managed const*, QV4::String*) 
==13626==    by 0x5FD012D: QV4::Object::hasOwnProperty(QV4::String*) const 
==13626==    by 0x5FD016A: QV4::Object::hasProperty(QV4::String*) const
==13626==    by 0x600E04F: QV4::Runtime::in(QV4::ExecutionContext*, QV4::ValueRef, QV4::ValueRef)