Lightman314
commented
5 months ago Considering that the MobSpawnType field of the MobSpawnEvent.FinalizeSpawn constructor (the event I listen to to define a mobs spawn-type) is not flagged @Nullable unlike the SpawnGroupData,CompoundTag, and BaseSpawner fields that follow. Therefore its input should not ever be a null value, same as the return value of MobSpawnEvent.FinalizeSpawn#getSpawnType.
I will add a null check to keep issues like this from occurring in the future, but I'm not going to expedite an update to fix an issue that isn't even my fault, so the fix will be posted whenever the next LC update comes out.
Butchercraft's developer really should be using NATURAL (when naturally spawned) or even MOB_SUMMONED (when summoned by another mob) for their spawn types, as null is not a valid input in that function.
Bonus Research:
I did some extra research after writing the above, and even the base EntityType#spawn function that they call doesn't have that field flagged as @Nonnull (and once again, the same function has other fields that are, so it's not an oversight or anything of the sorts), and Mojang always uses the NonNullByDefault flag on every class they ever make, so that is 100% not supposed to ever receive a null MobSpawnType like what ButcherCraft is giving it on lines 98/99 & 110/111 of their event listener class.
Edit:
For reference, here's my developer environments copy of the aforementioned EntityType#spawn function:
Minecraft Version
1.19.2
Forge Version
43.3.8
Lightman's Currency Version
2.2.1.2
Environment Type
Minecraft Client (Bug/crash happened in a single-player world or while the game was booting)
Other relevant Mods
Butchercraft 2.3.4
Describe the bug
Random crash when Butchercraft spawns a mob with an animal hood and several related animals around it. It does so with a
nullMobSpawnType, which is perfectly valid.To Reproduce
Screenshots/Logs/Crash Reports
https://gist.github.com/brisingraerowing/d3676dd14010717c1aa022fe763f3c39