---- Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 18/03/21, 12:40
Description: Exception in server tick loop

java.util.concurrent.CompletionException: u: Exception generating new chunk
	at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:314)
	at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:319)
	at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1155)
	at java.base/java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:478)
	at aau.b(SourceFile:58)
	at aqc.f(SourceFile:92)
	at aqc.a(SourceFile:132)
	at aqc.run(SourceFile:100)
	at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1429)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1016)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1665)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1598)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)
Caused by: u: Exception generating new chunk
	at aas.a(SourceFile:575)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at aas.a(SourceFile:557)
	at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146)
	... 11 more
Caused by: java.util.ConcurrentModificationException
	at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1225)
	at dam.b(SourceFile:63)
	at dam.a(SourceFile:53)
	at crp$a.a(SourceFile:113)
	at crp$a.a(SourceFile:62)
	at csb.a(SourceFile:277)
	at cpn.a(SourceFile:36)
	at cku.a(SourceFile:296)
	at cku.a(SourceFile:279)
	at ckw.e(SourceFile:53)
	at ckw.a(SourceFile:231)
	at aas.a(SourceFile:563)
	... 14 more


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
	Minecraft Version: 21w11a
	Minecraft Version ID: 21w11a
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 15.0.2, AdoptOpenJDK
	Java VM Version: OpenJDK 64-Bit Server VM (mixed mode, sharing), AdoptOpenJDK
	Memory: 7757124576 bytes (7397 MB) / 8623489024 bytes (8224 MB) up to 12884901888 bytes (12288 MB)
	CPUs: 8
	JVM Flags: 9 total; -Xmn256M -Xmx12G -Xss4M -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
	Player Count: 1 / 8; [abg['Wyk'/116, l='ServerLevel[New World]', x=784.92, y=70.53, z=-614.27]]
	Data Packs: vanilla
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.