Forge 39.0.45 has merged this pull request, which removed the BlockEntity#save(CompoundTag) method, which in turn renders the mod unusable since it's block makes use of this method.

Full crash report: https://gist.github.com/YuRaNnNzZZ/c66a4780c66102e42d846b89545a48da
Minecraft 1.18.1, Forge 39.0.45, mod version 1.1.2-1.18.1