Game crashed while loading chunks

The game crashed after teleporting to a location and then flying around in spectator. The full crash report is attached.

While searching for a duplicate, I came across MC-134762, but that appears to be a client crash.

1.14 Pre-Release 5\: [^crash-2019-04-20_01.07.58-server.txt]

---- Minecraft Crash Report ----
// Oops.

Time: 4/20/19 1:07 AM
Description: Exception ticking world

java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at bhu.a(SourceFile:72)
	at vg.a(SourceFile:317)
	at net.minecraft.server.MinecraftServer.b(SourceFile:827)
	at net.minecraft.server.MinecraftServer.a(SourceFile:764)
	at dxh.a(SourceFile:128)
	at net.minecraft.server.MinecraftServer.run(SourceFile:632)
	at java.lang.Thread.run(Thread.java:745)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Server thread
Stacktrace:
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at bhu.a(SourceFile:72)
	at vg.a(SourceFile:317)

-- Affected level --
Details:
	Level name: Gamemode4Dev 1.14
	All players: 1 total; [vh['misode'/256735, l='Gamemode4Dev 1.14', x=1560.98, y=77.48, z=-917.10]]
	Chunk stats: ServerChunkCache: 4153
	Level seed: 4922589396274518660
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: {}
	Level spawn location: World: (-192,73,-64), Chunk: (at 0,4,0 in -12,-4; contains blocks -192,0,-64 to -177,255,-49), Region: (-1,-1; contains chunks -32,-32 to -1,-1, blocks -512,0,-512 to -1,255,-1)
	Level time: 996930 game time, 1244 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 1 (now: false), thunder time: 1 (now: false)
	Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
	at net.minecraft.server.MinecraftServer.b(SourceFile:827)
	at net.minecraft.server.MinecraftServer.a(SourceFile:764)
	at dxh.a(SourceFile:128)
	at net.minecraft.server.MinecraftServer.run(SourceFile:632)
	at java.lang.Thread.run(Thread.java:745)

-- System Details --
Details:
	Minecraft Version: 1.14 Pre-Release 5
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 1253340424 bytes (1195 MB) / 2147483648 bytes (2048 MB) up to 2147483648 bytes (2048 MB)
	JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
	Player Count: 1 / 8; [vh['misode'/256735, l='Gamemode4Dev 1.14', x=1560.98, y=77.48, z=-917.10]]
	Data Packs: vanilla, file/base (incompatible), file/gm4_orbis (incompatible), file/gm4_cooler_caves (incompatible), file/gm4_dangerous_dungeons (incompatible), file/gm4_tower_structures (incompatible)
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.