---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 18.06.20, 09:55
Description: Exception in server tick loop

java.util.concurrent.CompletionException: s: 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 yr.b(SourceFile:58)
	at amq.e(SourceFile:94)
	at amq.a(SourceFile:137)
	at amq.run(SourceFile:105)
	at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1425)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:177)
Caused by: s: Exception generating new chunk
	at yp.a(SourceFile:579)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at yp.a(SourceFile:562)
	at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146)
	... 11 more
Caused by: java.util.ConcurrentModificationException
	at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1134)
	at cva.b(SourceFile:64)
	at cva.a(SourceFile:54)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at cqc.a(SourceFile:98)
	at cqc.a(SourceFile:131)
	at cpz.a(SourceFile:260)
	at cjs.a(SourceFile:40)
	at cjp$a.a(SourceFile:43)
	at cjp$a.a(SourceFile:34)
	at cml.a(SourceFile:249)
	at ckc.a(SourceFile:27)
	at cha.a(SourceFile:268)
	at cha.a(SourceFile:259)
	at chc.d(SourceFile:51)
	at chc.a(SourceFile:219)
	at yp.a(SourceFile:568)
	... 14 more


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- System Details --
Details:
	Minecraft Version: 1.16 Pre-release 8
	Minecraft Version ID: 1.16-pre8
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 12.0.1, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode, sharing), Oracle Corporation
	Memory: 478774048 bytes (456 MB) / 1040187392 bytes (992 MB) up to 2147483648 bytes (2048 MB)
	CPUs: 8
	JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
	Player Count: 1 / 8; [ze['violine1101'/215, l='ServerLevel[basalt tree]', x=82.53, y=51.00, z=-335.84]]
	Data Packs: vanilla
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.