Add-on seems broken because of Mantis Ticket No. 4130

[luzpaz]

https://tracker.freecadweb.org/view.php?id=4130
https://forum.freecadweb.org/viewtopic.php?f=3&t=36967
Specifically https://forum.freecadweb.org/viewtopic.php?f=3&t=36967&start=20#p361527