Hi all,

I recently updated my MDK from 1.18.1 to 1.18.2 whilst adding Parchment mappings, but when I clicked Singleplayer to create a new world, the game crashes:

https://gist.github.com/QuantumBlink1337/d88d50e0e846d2036517c1546813cfc4

 

I did attempt to add some ore generation code as I'm still new to Forge and want to practice, but I can't imagine it's related based on the stacktrace. I had this same crash with the recommended 40.1.0 Forge version.

Here's the repo for my mod:

https://github.com/QuantumBlink1337/Obsinite-Mod

That's a horrible error message.

First, the "mouseClicked event handler" is misleading. That's the thread name because it is running in response to you clicking something.

Its actually just a NullPointerException with no message.

Quote

java.lang.NullPointerException: mouseClicked event handler

at java.util.Objects.requireNonNull(Objects.java:208) ~[?:?] {}

at java.util.ImmutableCollections.listFromArray(ImmutableCollections.java:190) ~[?:?] {}

at java.util.List.of(List.java:1047) ~[?:?] {}

at java.util.ImmutableCollections.listCopy(ImmutableCollections.java:172) ~[?:?] {}

at java.util.List.copyOf(List.java:1068) ~[?:?] {}

at net.minecraft.core.HolderSet.direct(HolderSet.java:38) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.06.26-1.18.2-recomp.jar%2376!/:?] {re:classloading}

at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:197) ~[?:?] {}

at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1625) ~[?:?] {}

at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:509) ~[?:?] {}

at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:499) ~[?:?] {}

at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:921) ~[?:?] {}

at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?] {}

at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:682) ~[?:?] {}

at net.minecraft.world.level.biome.BiomeGenerationSettings$Builder.build(BiomeGenerationSettings.java:111) ~[forge-1.18.2-40.1.0_mapped_parchment_2022.06.26-1.18.2-recomp.jar%2376!/:?] {re:classloading,pl:accesstransformer:B}

You can see it is actually a problem in the biome generator. In fact it is in the feature part.

Somewhere along the way there is a null value and the error comes from it trying to insert it into an immutable list, which doesn't allow nulls

 

I think this NPE is caused by you not registering your configured feature. You just create one and then use Holder.direct() on it.

I posted a link to how botania does this in this thread: https://forums.minecraftforge.net/topic/113121-how-do-i-spawn-my-feature-in-the-world-1165/

but was told off because it uses a RegistryEvent<Feature> to do this instead of a DeferredRegistry. 🙂

I don't know of a good example using DeferredRegistrys given how features/placements get configured/registered and both methods ultimately do the same thing. Its just one is more declarative.

 

I am tempted to raise that error message as a bug in forge 🙂

Oh okay, that makes sense. I'll review my ore generation code and see if I can figure it out from there. What a terrible error message! Thanks for the help.