Check the reference count before deleting. Patch
as contributed on bug report.

Fixes: QTBUG-86547
Change-Id: I2cb197e3eeda7ade2442c23f6b4f1ae6ff2ff810
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
(cherry picked from commit af22ccf5

)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>