Hopper: java.lang.NullPointerException: Ticking memory connection

java.lang.NullPointerException: Ticking memory connection
	at atx.a(SourceFile:36)
	at atp.a(SourceFile:88)
	at apg.a(SourceFile:132)
	at mi.a(SourceFile:160)
	at aoj.a(SourceFile:781)
	at mi.c(SourceFile:95)
	at mh.<init>(SourceFile:31)
	at mg.a(SourceFile:212)
	at mg.a(SourceFile:249)
	at ld.a(SourceFile:155)
	at ld.c(SourceFile:206)
	at ld.a(SourceFile:100)
	at nd.c(SourceFile:87)
	at nd.a(SourceFile:52)
	at ef.a(SourceFile:166)

---- Minecraft Crash Report ----
// Hi. I'm Minecraft, and I'm a crashaholic.

Time: 25/10/13 16:17
Description: Ticking memory connection

java.lang.NullPointerException: Ticking memory connection
	at atx.a(SourceFile:36)
	at atp.a(SourceFile:88)
	at apg.a(SourceFile:132)
	at mi.a(SourceFile:160)
	at aoj.a(SourceFile:781)
	at mi.c(SourceFile:95)
	at mh.<init>(SourceFile:31)
	at mg.a(SourceFile:212)
	at mg.a(SourceFile:249)
	at ld.a(SourceFile:155)
	at ld.c(SourceFile:206)
	at ld.a(SourceFile:100)
	at nd.c(SourceFile:87)
	at nd.a(SourceFile:52)
	at ef.a(SourceFile:166)
	at ms.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsk.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at ky.run(SourceFile:617)


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

-- Head --
Stacktrace:
	at atx.a(SourceFile:36)
	at atp.a(SourceFile:88)
	at apg.a(SourceFile:132)
	at mi.a(SourceFile:160)
	at aoj.a(SourceFile:781)
	at mi.c(SourceFile:95)
	at mh.<init>(SourceFile:31)
	at mg.a(SourceFile:212)
	at mg.a(SourceFile:249)
	at ld.a(SourceFile:155)
	at ld.c(SourceFile:206)
	at ld.a(SourceFile:100)
	at nd.c(SourceFile:87)
	at nd.a(SourceFile:52)
	at ef.a(SourceFile:166)

-- Ticking connection --
Details:
	Connection: ef@9ff1d3
Stacktrace:
	at ms.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:529)
	at net.minecraft.server.MinecraftServer.t(SourceFile:441)
	at bsk.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at ky.run(SourceFile:617)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_17, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 114576424 bytes (109 MB) / 365404160 bytes (348 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 556 (31136 bytes; 0 MB) allocated, 556 (31136 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 62 (3472 bytes; 0 MB) allocated, 62 (3472 bytes; 0 MB) used
	Player Count: 1 / 8; [mm['MrTolai'/63, l='Mundo DE PRUEBAS', x=-94,63, y=4,30, z=805,96]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.