Prevent crash when destroying asynchronous Loader
Fixes: QTBUG-86255 Pick-to: 5.15 Change-Id: I30488b64d910a1409a43e2e98ee7ab084aec33d2 Reviewed-by: Ulf Hermann ulf.hermann@qt.io (cherry picked from commit 149c1dd0)
Fixes: QTBUG-86255 Pick-to: 5.15 Change-Id: I30488b64d910a1409a43e2e98ee7ab084aec33d2 Reviewed-by: Ulf Hermann ulf.hermann@qt.io (cherry picked from commit 149c1dd0)