qmltc: WebEngineView with anchors causes assertion at component creation

// Main.qml
import QtWebEngine

WebEngineView {
    anchors.left: undefined // or anchors.fill: parent
}

// main.cpp
#include <main.h>

int main(int argc, char **argv) {
    QtWebEngineQuick::initialize();
    QGuiApplication app{argc, argv};

    QQmlEngine engine;
    auto main = new App::Main(&engine); // Crashes here

    return app.exec();
}