Hopper: java.lang.NullPointerException: Ticking screen

java.lang.NullPointerException: Ticking screen
	at ef.a(SourceFile:154)
	at bfe.a(SourceFile:132)
	at bex.c(SourceFile:47)

---- Minecraft Crash Report ----
// On the bright side, I bought you a teddy bear!

Time: 10/25/13 7:36 AM
Description: Ticking screen

java.lang.NullPointerException: Ticking screen
	at ef.a(SourceFile:154)
	at bfe.a(SourceFile:132)
	at bex.c(SourceFile:47)
	at azd.o(SourceFile:1318)
	at azd.ad(SourceFile:753)
	at azd.e(SourceFile:704)
	at net.minecraft.client.main.Main.main(SourceFile:103)


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

-- Head --
Stacktrace:
	at ef.a(SourceFile:154)
	at bfe.a(SourceFile:132)
	at bex.c(SourceFile:47)

-- Affected screen --
Details:
	Screen name: bex
Stacktrace:
	at azd.o(SourceFile:1318)
	at azd.ad(SourceFile:753)
	at azd.e(SourceFile:704)
	at net.minecraft.client.main.Main.main(SourceFile:103)

-- System Details --
Details:
	Minecraft Version: 1.7.2
	Operating System: Windows 8 (amd64) version 6.2
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 321804616 bytes (306 MB) / 508493824 bytes (484 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
	Launched Version: 1.7.2
	LWJGL: 2.9.0
	OpenGL: Intel(R) HD Graphics 4000 GL version 4.0.0 - Build 9.17.10.2828, Intel
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: null
	Anisotropic Filtering: Off (1)