The bug
Going into a dimension that has height higher than the maximum height crashes the game. I just tried to get rid of that ceiling in the end. If you go to that dimension, the game crashes.
Stack trace
21w03a: [^crash-2021-01-23_20.18.51-server.txt]
Description: Exception in server tick loop
java.util.concurrent.CompletionException: u: Exception generating new chunk
at java.util.concurrent.CompletableFuture.encodeThrowable(Unknown Source)
at java.util.concurrent.CompletableFuture.completeThrowable(Unknown Source)
at java.util.concurrent.CompletableFuture.uniCompose(Unknown Source)
at java.util.concurrent.CompletableFuture$UniCompose.tryFire(Unknown Source)
at java.util.concurrent.CompletableFuture$Completion.run(Unknown Source)
at aak.b(SourceFile:58)
at aoz.e(SourceFile:94)
at aoz.a(SourceFile:137)
at aoz.run(SourceFile:105)
at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(Unknown Source)
at java.util.concurrent.ForkJoinTask.doExec(Unknown Source)
at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(Unknown Source)
at java.util.concurrent.ForkJoinPool.runWorker(Unknown Source)
at java.util.concurrent.ForkJoinWorkerThread.run(Unknown Source)
Caused by: u: Exception generating new chunk
at aai.a(SourceFile:573)
at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
at aai.a(SourceFile:556)
... 12 more
Caused by: java.lang.ArrayIndexOutOfBoundsException: 19
at cjq.b(SourceFile:216)
at cly.a(SourceFile:615)
at cjb.f(SourceFile:71)
at cjb$d.doWork(SourceFile:263)
at cjb.a(SourceFile:219)
at aai.a(SourceFile:562)
... 14 more
Please include a data pack or world to reproduce this