Hopper: java.lang.NullPointerException: Exception ticking world

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-449769/

Crash:

java.lang.NullPointerException: Exception ticking world
	at mh.c(SourceFile:199)
	at mi.b(SourceFile:120)

The following is the first clean report made public about this crash:

---- Minecraft Crash Report ----
// Don't be sad, have a hug! <3

Time: 10/23/13 7:45 PM
Description: Exception ticking world

java.lang.NullPointerException: Exception ticking world
	at mh.c(SourceFile:199)
	at mi.b(SourceFile:120)
	at net.minecraft.server.MinecraftServer.u(SourceFile:503)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsi.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kx.run(SourceFile:617)


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

-- Head --
Stacktrace:
	at mh.c(SourceFile:199)
	at mi.b(SourceFile:120)

-- Affected level --
Details:
	Level name: DrCataclysm
	All players: 0 total; []
	Chunk stats: ServerChunkCache: 499 Drop: 499
	Level seed: 590207505
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: World: (0,0,0), Chunk: (at 0,0,0 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 0 game time, 0 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at net.minecraft.server.MinecraftServer.u(SourceFile:503)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsi.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kx.run(SourceFile:617)

-- System Details --
Details:
	Minecraft Version: 1.7.1
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_40, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 265457176 bytes (253 MB) / 466616320 bytes (445 MB) up to 954728448 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 6334 (354704 bytes; 0 MB) allocated, 5028 (281568 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1257 (70392 bytes; 0 MB) allocated, 1257 (70392 bytes; 0 MB) used
	Player Count: 1 / 8; [ml['DrCataclysm'/381, l='DrCataclysm', x=-690.00, y=65.50, z=668.00]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-449769/20951086/