I had just started out in a freshly-made modpack, so there could be any number of factors at play here, but the first time I took damage from a mob, my game crashed out and the error message it threw cited LightWithin's code as the culprit. I wasn't doing anything special or weird when it happened, was just fighting a spider that attacked me. I've attached the crash report, please let me know if there's any other information you need from me :)

crash-2022-07-14_17.27.33-server.txt

Have you installed Factions as well? If yes what version? (It's not a requirement to run LightWithin but it's involved in the crash)

Ok nevermind, found the issue. I overcomplicated stuff a bit, should be fixed in the next version which is going to release later today I guess. If you want to play the meantime, you should add the factions mod. Sorry about that, and thanks for the report! Let me know if you need anything else!