Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at agc.a(SourceFile:163)
	at agc.d(SourceFile:191)

---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 07.09.13 00:25
Description: Exception generating new chunk

java.lang.NullPointerException
	at agc.a(SourceFile:163)
	at agc.d(SourceFile:191)
	at kc.c(SourceFile:72)
	at kb.<init>(SourceFile:28)
	at ka.a(SourceFile:209)
	at ka.d(SourceFile:343)
	at hw.d(SourceFile:211)
	at kl.a(SourceFile:272)
	at fd.a(SourceFile:136)
	at cv.b(SourceFile:64)
	at kl.e(SourceFile:63)
	at ko.b(SourceFile:37)
	at bnq.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bnn.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hr.run(SourceFile:575)


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

-- Head --
Stacktrace:
	at agc.a(SourceFile:163)
	at agc.d(SourceFile:191)

-- Chunk to be generated --
Details:
	Location: 44,10
	Position hash: 42949673004
	Generator: RandomLevelSource
Stacktrace:
	at kc.c(SourceFile:72)
	at kb.<init>(SourceFile:28)
	at ka.a(SourceFile:209)
	at ka.d(SourceFile:343)
	at hw.d(SourceFile:211)
	at kl.a(SourceFile:272)
	at fd.a(SourceFile:136)
	at cv.b(SourceFile:64)
	at kl.e(SourceFile:63)

-- Ticking connection --
Details:
	Connection: kl@41f7df0d
Stacktrace:
	at ko.b(SourceFile:37)
	at bnq.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.t(SourceFile:481)
	at net.minecraft.server.MinecraftServer.s(SourceFile:398)
	at bnn.s(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:332)
	at hr.run(SourceFile:575)

-- System Details --
Details:
	Minecraft Version: 13w36b
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 610828976 bytes (582 MB) / 1003880448 bytes (957 MB) up to 1003880448 bytes (957 MB)
	JVM Flags: 3 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -Xms1G
	AABB Pool Size: 6248 (349888 bytes; 0 MB) allocated, 5004 (280224 bytes; 0 MB) used
	IntCache: cache: 5, tcache: 14, allocated: 15, tallocated: 126
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1588 (88928 bytes; 0 MB) allocated, 956 (53536 bytes; 0 MB) used
	Player Count: 1 / 8; [kg['Kumasasa'/557438, l='New World33', x=803,52, y=123,17, z=335,99]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.