Minecraft hangs on world quit with "Couldn't load chunk" spamming log

I loaded a world from minecraft 1.12.2 in 18w22c and it worked fine. I waited a bit and saved the world. Nothing special in the log there. I restarted Minecraft and reloaded the world, and it started spamming the log. When I saved tried saving and quitting out of the world, the game would hang up with even more console spam.

I tested two worlds, and it happened with both, so I uploaded one of the worlds before the conversion to 18w22c. This can be reproduced every time.

[21:12:37] [Server thread/ERROR]: Couldn't load chunk
java.lang.NullPointerException: null
	at bzp.a(SourceFile:137) ~[18w22c.jar:?]
	at bzp.a(SourceFile:80) ~[18w22c.jar:?]
	at bqv.b(SourceFile:103) ~[18w22c.jar:?]
	at bqv.a(SourceFile:83) ~[18w22c.jar:?]
	at bqv.a(SourceFile:119) ~[18w22c.jar:?]
	at sl.g(SourceFile:92) [18w22c.jar:?]
	at sl.b(SourceFile:114) [18w22c.jar:?]
	at st.<init>(SourceFile:39) [18w22c.jar:?]
	at su.c(SourceFile:192) [18w22c.jar:?]
	at su.a(SourceFile:223) [18w22c.jar:?]
	at uy.a(SourceFile:274) [18w22c.jar:?]
	at uy.c(SourceFile:343) [18w22c.jar:?]
	at uy.a(SourceFile:167) [18w22c.jar:?]
	at tn.b(SourceFile:118) [18w22c.jar:?]
	at tn.Y_(SourceFile:65) [18w22c.jar:?]
	at hu.a(SourceFile:221) [18w22c.jar:?]
	at tk.c(SourceFile:175) [18w22c.jar:?]
	at net.minecraft.server.MinecraftServer.w(SourceFile:719) [18w22c.jar:?]
	at net.minecraft.server.MinecraftServer.v(SourceFile:626) [18w22c.jar:?]
	at dik.v(SourceFile:156) [18w22c.jar:?]
	at net.minecraft.server.MinecraftServer.run(SourceFile:531) [18w22c.jar:?]
	at java.lang.Thread.run(Thread.java:745) [?:1.8.0_51]