Modpack version
1.81a

Issue
No one was using the Alchemy array when we crashed

Logs
https://pastebin.com/gvEC9Yqj

Thanks for the report, I found the issue on the Blood Magic issue tracker (linked above). I recommend removing the Alchemy Array with something like MCEdit.

I do not believe I can fix this, and the majority of modders no longer support 1.12, so I'll close this issue.

Nethertheless, thank you for reporting :)