OSX: Crash when using application menu after closing a main window

When opening multiple QMainWindows and closing one, the app crashes when using the application menu.

Testcase:
start qtbase/examples/widgets/mainwindows/sdi/sdi.app
open a second window
close the newly opened window
click on "sdi" in the menu bar
->crash

This happens with every app using menu items, which get merged into the application menu (about, preferences, exit).
It seems like closing a main window does cleanup its menu including merged items, but that the merged items are still referenced.