QML engine mis-converts QQmlListProperty

Consider:

import QtQml

QtObject {
    property list<QtObject> objs: [
        QtObject {},
        QtObject {}
    ]

    function returnObjs() : list<QtObject> {
        objs.push(this); // do something we cannot compile to C++
        return objs
    }

    Component.onCompleted: {
        var local = returnObjs();
        console.log(local[0], local[1], local[2]);
    }
}

This crashes when compiled to C++. The onCompleted handler is compiled to C++ and the returnObjs() function is not. However, the engine cannot properly convert QQmlListProperty to itself and returns a default-constructed list property there. The default-constructed list property does not have an at() method, which we assume to be available in generated code.