After reporting the same issue to the Guns RPG dev, they replied that the two mods are incompatible because they both use the same perks folder, causing a conflict.

Full quote from the dev:
"I'd suggest to create issue on Astral Sorcery github.
Cause of this is that we use perks data directory with 2 completely different perk data structures so neither of these 2 mods can load all data.
On our side all json errors are handled by skipping loading and just logging error. I'd suggest to do the same"
/
"our perks are conflicting with their perks as same folder for it is used. I cannot really do much on our side except changing the folder name, which is not a solution. I'd say to create issue on their github so they change their implementation to not completely crash when invalid data are being loaded (for example we just skip the invalid file loading and log error, but on their side the error is not handled at all, which stops the data loading and crashes)"

Logs from my own crash on world loading:
latest.log
debug.log