Crash when generating near top of world

The bug

When creating a superflat world with the top block level at 250+ the game crashes during generation or almost immediately after entering the world.

Disabling surface structures like villages seems to avoid the problem. Enabling normal decoration like trees and grass also works fine, with one exception when testing a mushroom biome world with only decoration.

Unsure if other world types or dimensions would have the same problem since without the Customized type there's no (vanilla) way to force generation near the world top.

Crash report

1.13.1\: [^crash-2018-08-26_22.11.08-server.txt]

Description: Exception generating new chunk

java.util.concurrent.CompletionException: java.lang.ArrayIndexOutOfBoundsException: 16
	at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273)
	at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280)
	at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:604)
	at java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:577)
	at java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:443)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1692)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
Caused by: java.lang.ArrayIndexOutOfBoundsException: 16
	at bnq.a(SourceFile:87)
	at bnq.e(SourceFile:496)
	at bxa.a(SourceFile:269)
	at bxg$g.a(SourceFile:881)
	at bxb.a(SourceFile:62)
	at btk.a(SourceFile:78)
	at bvp.a(SourceFile:16)
	at bvp.a(SourceFile:13)
	at bpm.a(SourceFile:27)
	at ayt.a(SourceFile:504)
	at boo.a(SourceFile:183)
	at tr.a(SourceFile:12)
	at tq.a(SourceFile:35)
	at bnc.a(SourceFile:95)
	at tx.a(SourceFile:79)
	at tx.a(SourceFile:25)
	at acu$a.a(SourceFile:147)
	at java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:602)
	... 6 more