Crash when running LAN server

[kaydenvg]

Getting a pretty consistent crash when running a LAN server. All players have the mod installed, could be caused by one or more players venturing far from the host and trying to generate terrain? I should mention I have other world gen mods installed but none so far have caused crashes in singleplayer.

Stacktrace:
at knot//com.google.common.collect.ImmutableCollection.add(ImmutableCollection.java:264)
at knot//net.countered.terrainslabs.worldgen.slabfeature.SlabFeatureLogic.storeSlabPositions(SlabFeatureLogic.java:69)
at knot//net.countered.terrainslabs.worldgen.slabfeature.SlabFeatureLogic.method_13151(SlabFeatureLogic.java:43)
at knot//net.minecraft.class_2975.method_12862(class_2975.java:537)
at knot//net.minecraft.class_6796.method_39646(class_6796.java:54)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(Unknown Source)
at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Unknown Source)
at java.base/java.util.stream.ReferencePipeline$Head.forEach(Unknown Source)
at java.base/java.util.stream.ReferencePipeline$7$1.accept(Unknown Source)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(Unknown Source)
at java.base/java.util.stream.IntPipeline$1$1.accept(Unknown Source)
at java.base/java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Unknown Source)
at java.base/java.util.Spliterator$OfInt.forEachRemaining(Unknown Source)
at java.base/java.util.stream.AbstractPipeline.copyInto(Unknown Source)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)
at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(Unknown Source)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(Unknown Source)
at java.base/java.util.stream.AbstractPipeline.evaluate(Unknown Source)
at java.base/java.util.stream.ReferencePipeline.forEach(Unknown Source)
at java.base/java.util.stream.ReferencePipeline$7$1.accept(Unknown Source)
at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Unknown Source)
at java.base/java.util.stream.AbstractPipeline.copyInto(Unknown Source)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(Unknown Source)
at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(Unknown Source)
at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(Unknown Source)
at java.base/java.util.stream.AbstractPipeline.evaluate(Unknown Source)
at java.base/java.util.stream.ReferencePipeline.forEach(Unknown Source)
at knot//net.minecraft.class_6796.method_39648(class_6796.java:53)
at knot//net.minecraft.class_6796.method_39650(class_6796.java:42)
at knot//net.minecraft.class_2794.method_12102(class_2794.java:357)
at knot//net.minecraft.class_2806.method_51375(class_2806.java:108)

[Coun7ered]

Not sure if I can reproduce the issue. Does this happen in the new 1.21.11 version or are you on a different version? And on Fabric or with Sinytra?