https://gist.github.com/ProsperCraft/47193dcd22b1fe9004ca3c9cd3a831d7

On a dedicated server on load.

callablehorses-1.16.3-1.2.1.4
forge-1.16.5-36.2.16

same, any solution?

This is still happening with forge .36 fix please?

Same at 1.18.2, any idea ?

@ProsperCraft @Cusssy @thanksshu I'm quite late but I think I actually figured it out 🤣 there's one missing line on horse_drop.json inside the mod, adding it partially fixes the Disable Horse Drops setting. Note that the horse drop setting itself doesn't seem to be implemented and is forced to be always on (which behaves like OFF because the json file is broken).
If you were to replace the horse_drops.json inside the mod's jar with the one from my pull request, it is very likely to disable callable horse drops and stop the console error without issues.
For actually fixing the setting, my pull request also includes that but that requires recompiling the mod. I think everything works fine with my pull request, it seemed like so. No errors, and intended behavior. Note that this repo seems to be on 1.3.0.0 of the mod instead of 1.3.0.1 and I have no idea what was fixed in .1. That's for 1.20 but other versions are also affected