Some calling code did this beforehand, other didn't. Now, the function
itself checks for an existing handler before doing anything else.
Change-Id: I8fc43fb8788c9dfe825b15ffa2fa69ee43915cd6
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>