QQuickWidget Segmentation Fault in setSource

If the root object of a Qml document is unknown to QQuickWidget (e.g. if it's not a QQuickItem or a QWindow), then setSource fails with segmentation fault. An example is the existing QML file in the QtDeclarative source code:

qtdeclarative/src/quickdialogs/quickdialogsquickimpl/qml/+Fusion/ColorDialog.qml

The root object in this file is ColorDialogImpl, as a result, when I try to load the file in a QQuickWidget (QQuickWidget::setSource), I get segmentation fault.

The segfault happens with the following message:

QQuickWidget only supports loading of root objects that derive from QQuickItem. 
Ensure your QML code is written for QtQuick 2, and uses a root that is or 
inherits from QtQuick's Item (not a Timer, QtObject, etc). 

Stack trace:
https://dpaste.org/XEJvB
The code and more info can be found under the patch:
https://codereview.qt-project.org/c/qt/qttools/+/624096/comments/9f458086_57a4276d