I was getting the error
Error: /home/$USER/.config/aseprite/extensions/losepec-palette-importer/./lospec-palette-importer.lua:191: unexpected end of input
on the Steam version on Linux (Manjaro). I launched the programme from the command line directly from /home/$USER/.local/share/Steam/steamapps/common/Aseprite
so I could see logs and potentially debug it a little more but when launching it this way instead of through Steam the script ran fine.
Might be helpful as a workaround to anyone who needs it or the developer for figuring out what the problem is.