Can't import from Firefox

[Krzmbrzl]

I'm on KDE Neon (based on Ubuntu 22.04) and have Firefox installed via apt (v114.0). I also installed JabRef from a provided Deb package and have version 5.9 installed.

I checked the manual installation instructions and as far as I can tell, my setup seems to be alright, except that I don't have /usr/lib64/mozilla on my system - only /usr/lib/mozilla and therefore I only have the respective JSON file in that directory.

The path references in the JSON file does exist and the Python script has execute permissions for everyone.

Here's what the Browser console has to say when this issue occurs:
console_output.txt

Any idea what might be the issue here?

If I remember correctly, my JabRef setup on this particular computer has worked before, but there was a FF update today and now it no longer works. So either I am misremembering having used the Browser import function on this PC before or the recent update broke something.