Modtweaker Logs gives NPE when removing a variation!

[Guinaro]

I'm currently using the Modtweaker functionctionality as implemented by Jared in issue #586
And I'm experiencing a Null Pointer Exception:

The strange thing is that the removal is indeed performed and executed in game, but you still get an NPE.

Relevant Log Part:
[AVAILABLE][CLIENT][INFO] Removing chisel group called: granite
[AVAILABLE][CLIENT][ERROR] Error while applying actions
java.lang.NullPointerException
    at team.chisel.common.carving.GroupList.removeVariation(GroupList.java:259)
    at team.chisel.common.carving.GroupList.removeVariation(GroupList.java:231)
...

Script Used:

import mods.chisel.Carving;

//Remove Granite from the Granite Chisel Group
Carving.removeVariation("granite", <minecraft:stone:1>);

Gist with extended error message and script:
https://gist.github.com/Guinaro/271882fd4306b2bfcbed26763648bf14

Guinaro

[tterrag1098]

This error seems impossible...the only way I can see it happening is if someone has added a group to the list with a null name. You are on the latest version of Chisel, correct? I will add some safety checks in the next version.

[Guinaro]

Yes Using Chisel-MC1.12.2-0.2.0.31.
If you need more info, just ask. But it could indeed very well be that one of the 245 mods I'm loading is doing something unexpected, and loading a null name wouldn't surprise me. Sometimes running commands in game fails, because of the same reason, but finding the culprit is something else.

Guinaro

[Ashendale]

I just wanted to add that removing a group spits out a similar error.

Using:

import mods.chisel.Carving;

mods.chisel.Carving.removeGroup("blockInvar");

I get:

[AVAILABLE][CLIENT][INFO] Removing chisel group called: blockInvar
[AVAILABLE][CLIENT][ERROR] Error while applying actions
java.util.ConcurrentModificationException
	at java.util.HashMap$HashIterator.nextNode(Unknown Source)
	at java.util.HashMap$EntryIterator.next(Unknown Source)
	at java.util.HashMap$EntryIterator.next(Unknown Source)
	at com.google.common.collect.AbstractMapBasedMultimap$AsMap$AsMapIterator.next(AbstractMapBasedMultimap.java:1428)
	at com.google.common.collect.AbstractMapBasedMultimap$AsMap$AsMapIterator.next(AbstractMapBasedMultimap.java:1417)
	at com.google.common.collect.TransformedIterator.next(TransformedIterator.java:47)
	at team.chisel.common.carving.Carving.removeGroup(Carving.java:198)
	at com.blamejared.compat.chisel.Carving$ActionRemoveGroup.apply(Carving.java:104)
	at crafttweaker.runtime.CrTTweaker.apply(CrTTweaker.java:51)
	at crafttweaker.CraftTweakerAPI.apply(CraftTweakerAPI.java:135)
	at java.lang.Iterable.forEach(Unknown Source)
	at com.blamejared.ModTweaker.loadComplete(ModTweaker.java:42)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at net.minecraftforge.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:627)
	at sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
	at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
	at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
	at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
	at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
	at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
	at com.google.common.eventbus.EventBus.post(EventBus.java:217)
	at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:218)
	at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:196)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
	at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
	at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
	at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
	at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
	at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
	at com.google.common.eventbus.EventBus.post(EventBus.java:217)
	at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:135)
	at net.minecraftforge.fml.common.Loader.initializeMods(Loader.java:752)
	at net.minecraftforge.fml.client.FMLClientHandler.finishMinecraftLoading(FMLClientHandler.java:329)
	at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:534)
	at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
	at net.minecraft.client.main.Main.main(SourceFile:123)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
	at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.multimc.onesix.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:196)
	at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:231)
	at org.multimc.EntryPoint.listen(EntryPoint.java:143)
	at org.multimc.EntryPoint.main(EntryPoint.java:34)