KDE/plasma 'open with' > core dump with non-existent locale

When in Plasma's 'System Settings' > 'Region & Language' a locale is chosen that is not actually installed (generated) mkvtoolnix-gui crashes when 'open with' is used from Dolphin. This also happens (in some cases) when the program is started from the menu.

For example: 'English (Netherlands)' can be chosen as a locale, but no such locale exists on the system. There is no en_NL.* of any kind in /etc/locale.gen, but KDE/plasma appears to know what to do... until you try to 'open with' a file with mkvtoolnix-gui. There is no message but the system log files show a core dump. From the command line the problem does not occur. Something like "mkvtoolnix-gui ./some.mkv" works fine.

The bug never fails: I have experienced this with kde/plasma on Debian 11, Fedora 38 and Kubuntu 20.04.

Plasma 5.27.4

MKVToolnix GUI v 47.0.0