Provided log: https://mclo.gs/SU1e9Rn
Line 688 and 690 are relevant, something about mistmatching registries when adding a custom Forge Controller Block via Alloy Forgery. Needs investigating.

After more extensive testing this issue isn't consistently reproducible. Its likely sole mod compat issue. This will be worked on more later, but until a more reliable reproduction setup is found this issue will stay closed.