This bug results from QTBUG-108612.
QtWebEngine uses foreign types in form of:
which is used for example like:
The issue that QWebEngineCertificateError has only a copy constructor , but it is used here as value type. This is not correct as value types should have a default constructor. We do not want to use anonymous qml elements as our classes need proper documentation, therefore qml elements have to stayed named.
Instead we would like to use a value type which is QML_UNCREATABLE which would mean it can not be used as a property and it does not have a default constructor.
This way we have value proper semantic , with value not instanceable by user , passed (copied) in various signal handlers.