Not possible to accept QWebEngineFullScreenRequest asynchronously

It is not possible to call QWebEngineFullScreenRequest.accept() anywhere other than in the SLOT connected to fullScreenRequested(). Doing so results in the error:
Cannot accept QWebEngineFullScreenRequest: Originating page is already deleted

The page has not been deleted. Calling accept() in the SLOT works fine.

This bug means that it is not possible to ask the user for permission to switch to full screen.

I dont know if the underlying chromium APIs allow this to be asynchronous. If not, then perhaps the documentation of QWebEngineFullScreenRequest should be updated to make this clear.