Not entirely sure what happened, but I think that when trying to use the lightwells for making lava, they don't appreciate having blocks over the light well (not ontop of, but a few blocks above), as it crashed the server I was on the instant I linked it to the light well. Log is as follows:

https://pastebin.pl/view/34c80f76

Edit:
Forge 31.2.37
Astral (1.15.2) 1.12.9

For clarification, you linked a collector crystal to a lightwell that didn't have sky access, and that's when the error occurred?

Shoot i'm sorry for not getting back sooner I've been busy and distracted, Yes. The crash only happened after I tried to link the collector crystal to a light well that didn't have direct LoS to the sky, it had some stairs placed over the top of it