17w49a Crash Report - Unable to load world

---- Minecraft Crash Report ----
// Who set us up the TNT?

Time: 7/12/17 5:48 PM
Description: Exception in server tick loop

java.lang.NullPointerException: Exception in server tick loop
	at jx.<init>(SourceFile:47)
	at nl.b(SourceFile:146)
	at bme.b(SourceFile:87)
	at bmi.a(SourceFile:76)
	at bmi.a(SourceFile:53)
	at bmi.a(SourceFile:34)
	at qr.b(SourceFile:159)
	at clf.a(SourceFile:96)
	at clf.d(SourceFile:128)
	at net.minecraft.server.MinecraftServer.run(SourceFile:467)
	at java.lang.Thread.run(Thread.java:745)


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
	Minecraft Version: 17w49a
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 63493192 bytes (60 MB) / 150994944 bytes (144 MB) up to 1073741824 bytes (1024 MB)
	JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Player Count: 0 / 8; []
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.