[MC-134872] Game crashes after loading world 100%

Client loads fine and loads the game to select your save. I open up the game and sticks to 68% for a bit, and then quickly after reaching 100% the game crashes every time. I have some saves from version 1.12 that also won't load.

Not sure if its relevant, but this particular world loaded on a small island surrounded with TONS of seaweed. Not sure if all that wiggling from the seaweed has any affect on this. Wasn't sure if any other actual world elements have an effect, but I haven't ventured off the island, so I wouldn't expect many chunks have been generated yet. I tried reducing all the graphics settings to minimum to see if it would help but no luck.

1.13: crash-2018-07-25_15.37.21-server.txt

---- Minecraft Crash Report ----
// Why did you do that?

Time: 7/25/18 3:37 PM
Description: Ticking memory connection

java.lang.IllegalStateException: Not a JSON Object: null
	at com.google.gson.JsonElement.getAsJsonObject(JsonElement.java:90)
	at wn.a(SourceFile:82)
	at wn.<init>(SourceFile:48)
	at vo.a(SourceFile:915)
	at te.<init>(SourceFile:159)
	at vo.g(SourceFile:442)
	at ud.b(SourceFile:113)
	at ud.Y_(SourceFile:65)
	at hw.a(SourceFile:238)
	at ua.c(SourceFile:171)
	at net.minecraft.server.MinecraftServer.w(SourceFile:749)
	at net.minecraft.server.MinecraftServer.v(SourceFile:656)
	at dfx.v(SourceFile:157)
	at net.minecraft.server.MinecraftServer.run(SourceFile:559)
	at java.lang.Thread.run(Thread.java:748)


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

-- Head --
Thread: Server thread
Stacktrace:
	at com.google.gson.JsonElement.getAsJsonObject(JsonElement.java:90)
	at wn.a(SourceFile:82)
	at wn.<init>(SourceFile:48)
	at vo.a(SourceFile:915)
	at te.<init>(SourceFile:159)
	at vo.g(SourceFile:442)
	at ud.b(SourceFile:113)
	at ud.Y_(SourceFile:65)
	at hw.a(SourceFile:238)

-- Ticking connection --
Details:
	Connection: hw@3524af1
Stacktrace:
	at ua.c(SourceFile:171)
	at net.minecraft.server.MinecraftServer.w(SourceFile:749)
	at net.minecraft.server.MinecraftServer.v(SourceFile:656)
	at dfx.v(SourceFile:157)
	at net.minecraft.server.MinecraftServer.run(SourceFile:559)
	at java.lang.Thread.run(Thread.java:748)

-- System Details --
Details:
	Minecraft Version: 1.13
	Operating System: Linux (amd64) version 4.15.0-29-generic
	Java Version: 1.8.0_171, Oracle Corporation
	Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 515229120 bytes (491 MB) / 1174405120 bytes (1120 MB) up to 2147483648 bytes (2048 MB)
	JVM Flags: 7 total; -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
	Profiler Position: N/A (disabled)
	Player Count: 0 / 8; []
	Data Packs: vanilla
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.