fix SurfaceRuleProcessor chunk unavailable crash during world generation

Author: yynps

gradle.properties

@@ -1,4 +1,4 @@
-org.gradle.jvmargs=-Xmx3G
+org.gradle.jvmargs=-Xmx2G -XX:+UseG1GC -XX:MaxGCPauseMillis=200
 org.gradle.daemon=false
 org.gradle.debug=false
 
@@ -9,7 +9,7 @@ neoForge.parchment.mappingsVersion=2024.06.23
 mod_id=aether
 mod_group=com.aetherteam.aether
 mod_name=The Aether
-mod_version=1.5.11
+mod_version=1.5.12
 mod_license=Assets: All Rights Reserved; Code: LGPL-3.0
 mod_url=https://modrinth.com/mod/aether
 mod_update=https://github.com/The-Aether-Team/The-Aether/raw/1.21.1-develop/update.json

src/main/java/com/aetherteam/aether/world/processor/SurfaceRuleProcessor.java

@@ -54,7 +54,17 @@ public StructureTemplate.StructureBlockInfo process(LevelReader level, BlockPos
                     NoiseChunk noisechunk = ((ChunkAccessAccessor) chunkAccess).aether$getNoiseChunk();
                     if (noisechunk != null) {
                         CarvingContext carvingcontext = new CarvingContext(noiseBasedChunkGenerator, worldGenLevel.registryAccess(), chunkAccess.getHeightAccessorForGeneration(), noisechunk, serverChunkCache.randomState(), surfaceRule);
-                        Optional<BlockState> state = carvingcontext.topMaterial(worldGenLevel.getBiomeManager()::getNoiseBiomeAtPosition, chunkAccess, modifiedBlockInfo.pos(), false);
+                        // [uto26] Wrap topMaterial in try-catch: biome sampling via BiomeManager.getNoiseBiomeAtPosition
+                        // can reach into neighboring chunks outside the WorldGenRegion during structure generation,
+                        // causing IllegalStateException from WorldGenRegion.getChunk(). When this happens, fall back
+                        // to the unmodified block info (structure uses default Aether surface block).
+                        Optional<BlockState> state;
+                        try {
+                            state = carvingcontext.topMaterial(worldGenLevel.getBiomeManager()::getNoiseBiomeAtPosition, chunkAccess, modifiedBlockInfo.pos(), false);
+                        } catch (IllegalStateException e) {
+                            // Chunk unavailable during world generation — skip surface rule replacement
+                            return modifiedBlockInfo;
+                        }
                         if (state.isPresent()) {
                             if (modifiedBlockInfo.state().is(AetherTags.Blocks.AETHER_DIRT) && !modifiedBlockInfo.state().is(AetherBlocks.AETHER_DIRT.get()) && state.get().is(AetherTags.Blocks.AETHER_DIRT)) {
                                 return new StructureTemplate.StructureBlockInfo(modifiedBlockInfo.pos(), state.get(), null);