[MC-187408] Game crashing with Nether portals - java.lang.NullPointerException: Ticking player

Moderator Note

Worlds newly generated in 1.16 Pre-release 1 are corrupted beyond simple repair. The part of the level.dat file that stores dimensions has gone missing, meaning that these worlds do not have a Nether or End. [Mojang] slicedlime has a full explanation in this Pre-release 2 video here, along with some potential ways on how to fix it - though we thoroughly recommend to instead just discard the world.

Built a portal, game crashed before loading Nether.

Stack trace

1.16-pre1: crash-2020-06-04_16.23.07-server.txt

Description: Ticking player

java.lang.NullPointerException: Ticking player
	at ze.a(SourceFile:651)
	at aoj.bg(SourceFile:1900)
	at aoj.ad(SourceFile:437)
	at aov.ad(SourceFile:320)
	at aoj.j(SourceFile:419)
	at aov.j(SourceFile:2181)
	at bdy.j(SourceFile:275)
	at ze.w_(SourceFile:418)
	at zv.b(SourceFile:206)
	at me.a(SourceFile:234)
	at zu.c(SourceFile:171)
	at net.minecraft.server.MinecraftServer.b(SourceFile:885)
	at net.minecraft.server.MinecraftServer.a(SourceFile:812)
	at eov.a(SourceFile:93)
	at net.minecraft.server.MinecraftServer.v(SourceFile:671)
	at net.minecraft.server.MinecraftServer.a(SourceFile:256)
	at java.lang.Thread.run(Thread.java:745)