Minecraft Version: 1.18.2
DynamicTrees-BOP version [DynamicTreesBOP-1.18.2-3.0.0-ALPHA1.jar]

In therealeststu.dtbop.genfeature.AlternativeLeavesGenFeature.postGenerate(AlternativeLeavesGenFeature.java:51) the PostGenerationContext is requesting a Bounds index 0 of a length 0 array.

It appeared to be within a Mystical Forest if that helps

Crash log:
Caused by: java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0 at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64) at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70) at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266) at java.base/java.util.Objects.checkIndex(Objects.java:359) at java.base/java.util.ArrayList.get(ArrayList.java:427) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.util.BlockBounds.<init>(BlockBounds.java:68) at TRANSFORMER/[email protected]/therealeststu.dtbop.genfeature.AlternativeLeavesGenFeature.postGenerate(AlternativeLeavesGenFeature.java:51) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.systems.genfeatures.GenFeature$Type.generate(GenFeature.java:196) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.systems.genfeatures.GenFeature.generate(GenFeature.java:105) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.systems.genfeatures.GenFeatureConfiguration.generate(GenFeatureConfiguration.java:50) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.trees.Species.lambda$postGeneration$16(Species.java:2062) at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.trees.Species.postGeneration(Species.java:2061) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.worldgen.JoCode.generate(JoCode.java:246) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.trees.Species.generate(Species.java:1975) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.worldgen.TreeGenerator.makeTree(TreeGenerator.java:139) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.worldgen.TreeGenerator.makeTrees(TreeGenerator.java:103) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.worldgen.DynamicTreeFeature.lambda$place$0(DynamicTreeFeature.java:48) at java.base/java.util.ArrayList.forEach(ArrayList.java:1511) at TRANSFORMER/[email protected]/com.ferreusveritas.dynamictrees.worldgen.DynamicTreeFeature.m_142674_(DynamicTreeFeature.java:48) at TRANSFORMER/[email protected]/net.minecraft.world.level.levelgen.feature.Feature.m_204740_(Feature.java:153) at TRANSFORMER/[email protected]/net.minecraft.world.level.levelgen.feature.ConfiguredFeature.m_65385_(ConfiguredFeature.java:27) at TRANSFORMER/[email protected]/net.minecraft.world.level.levelgen.placement.PlacedFeature.m_191789_(PlacedFeature.java:56) at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) at TRANSFORMER/[email protected]/net.minecraft.world.level.levelgen.placement.PlacedFeature.m_191797_(PlacedFeature.java:55) at TRANSFORMER/[email protected]/net.minecraft.world.level.levelgen.placement.PlacedFeature.m_191806_(PlacedFeature.java:44) at TRANSFORMER/[email protected]/com.terraforged.mod.worldgen.cave.NoiseCaveDecorator.decorate(NoiseCaveDecorator.java:72) at TRANSFORMER/[email protected]/com.terraforged.mod.worldgen.cave.NoiseCaveDecorator.decorate(NoiseCaveDecorator.java:51) at TRANSFORMER/[email protected]/com.terraforged.mod.worldgen.cave.NoiseCaveGenerator.decorate(NoiseCaveGenerator.java:84) at TRANSFORMER/[email protected]/com.terraforged.mod.worldgen.biome.BiomeGenerator.decorate(BiomeGenerator.java:78) at TRANSFORMER/[email protected]/com.terraforged.mod.worldgen.Generator.m_183372_(Generator.java:208) at TRANSFORMER/[email protected]/net.minecraft.world.level.chunk.ChunkStatus.m_187807_(ChunkStatus.java:135) at TRANSFORMER/[email protected]/net.minecraft.world.level.chunk.ChunkStatus.m_187788_(ChunkStatus.java:262) at TRANSFORMER/[email protected]/net.minecraft.server.level.ChunkMap.lambda$scheduleChunkGeneration$22(ChunkMap.java:589) ... 14 more

Please try this patch and let me know if you are still having the issue https://legacy.curseforge.com/minecraft/mc-mods/dtbop/files/4535955

I'm going to assume this fixed. If you encounter the issue on the latest version let us know.