Game crashes with 'Exception generating new chunk'

The bug

Upgrade from 1.10.2. One crash. Chunks aren't generating. Gamemode creative/survival no longer works. Can't leave Spectator Mode. Can't exit the game normally. Must close app.

Crash report

1.13-pre4 (from MC-132178

Time: 6/27/18 12:00 PM
Description: Exception generating new chunk

java.util.concurrent.ExecutionException: java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
	at java.util.concurrent.CompletableFuture.reportGet(Unknown Source)
	at java.util.concurrent.CompletableFuture.get(Unknown Source)
	at sw.c(SourceFile:126)
	at te.a(SourceFile:85)
	at tf.c(SourceFile:122)
	at sx.i_(SourceFile:221)
	at net.minecraft.server.MinecraftServer.w(SourceFile:696)
	at si.w(SourceFile:356)
	at net.minecraft.server.MinecraftServer.v(SourceFile:630)
	at net.minecraft.server.MinecraftServer.run(SourceFile:535)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
	at java.util.ArrayList.rangeCheck(Unknown Source)
	at java.util.ArrayList.set(Unknown Source)
	at bru.<init>(SourceFile:137)
	at brv.b(SourceFile:87)
	at brv.f(SourceFile:123)
	at brq.a(SourceFile:156)
	at sw.f(SourceFile:327)
	at bxg.a(SourceFile:223)
	at bxg.a(SourceFile:71)
	at bzm.a(SourceFile:16)
	at bzm.a(SourceFile:13)
	at bti.a(SourceFile:27)
	at bct.a(SourceFile:515)
	at bqu.a(SourceFile:109)
	at tl.a(SourceFile:12)
	at tk.a(SourceFile:35)
	at bqy.a(SourceFile:95)
	at tr.a(SourceFile:62)
	at tr.a(SourceFile:25)
	at ahb$a.a(SourceFile:130)
	at java.util.concurrent.CompletableFuture.uniApply(Unknown Source)
	at java.util.concurrent.CompletableFuture$UniApply.tryFire(Unknown Source)
	at java.util.concurrent.CompletableFuture$Completion.exec(Unknown Source)
	at java.util.concurrent.ForkJoinTask.doExec(Unknown Source)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(Unknown Source)
	at java.util.concurrent.ForkJoinPool.runWorker(Unknown Source)
	at java.util.concurrent.ForkJoinWorkerThread.run(Unknown Source)

18w22b\: [^crash-2018-05-31_02.20.41-server.txt]

Description: Exception generating new chunk

java.util.concurrent.ExecutionException: java.lang.UnsupportedOperationException
	at java.util.concurrent.CompletableFuture.reportGet(Unknown Source)
	at java.util.concurrent.CompletableFuture.get(Unknown Source)
	at sl.c(SourceFile:126)
	at st.a(SourceFile:84)
	at su.c(SourceFile:143)
	at sm.i_(SourceFile:223)
	at net.minecraft.server.MinecraftServer.w(SourceFile:693)
	at net.minecraft.server.MinecraftServer.v(SourceFile:626)
	at dik.v(SourceFile:156)
	at net.minecraft.server.MinecraftServer.run(SourceFile:531)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.UnsupportedOperationException
	at bpy.e(SourceFile:100)
	at sr.i(SourceFile:245)
	at sr.a(SourceFile:238)
	at bsk.a(SourceFile:29)
	at bsk.a(SourceFile:13)
	at bss.a(SourceFile:21)
	at bss.a(SourceFile:13)
	at bsn.a(SourceFile:27)
	at bca.a(SourceFile:515)
	at bqa.a(SourceFile:109)
	at ta.a(SourceFile:12)
	at sz.a(SourceFile:34)
	at bqe.a(SourceFile:95)
	at tg.a(SourceFile:62)
	at tg.a(SourceFile:25)
	at agi$a.a(SourceFile:131)
	at java.util.concurrent.CompletableFuture.uniApply(Unknown Source)
	at java.util.concurrent.CompletableFuture$UniApply.tryFire(Unknown Source)
	at java.util.concurrent.CompletableFuture$Completion.exec(Unknown Source)
	at java.util.concurrent.ForkJoinTask.doExec(Unknown Source)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(Unknown Source)
	at java.util.concurrent.ForkJoinPool.runWorker(Unknown Source)
	at java.util.concurrent.ForkJoinWorkerThread.run(Unknown Source)