Arranging QDockWidgets programatically causes segmentation faults

When arranging QDockWidgets programatically, the program segfaults.

I'll attach a minimal example, derived from KGeoTag (but stripped down to Qt only, no KDE dependencies). Maybe this also works with fewer dock widgets and/or a less complex arrangement. However, using this example, I can reliably produce a segfault when starting "View" → "Set default dock arrangement". Interestingly, this does not always happen on first try. Most of the times it does, but sometimes, I have to run the function two times or even four or five times before the crash occurs. But it does crash every time.

However, the backtrace always looks similar. I'll also attach one.