Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at ayr.a(SourceFile:200)
	at ayi.b(SourceFile:382)
	at ayi.a(SourceFile:259)
	at ayq.a(SourceFile:122)

---- Minecraft Crash Report ----
// Oh - I know what I did wrong!

Time: 20.09.13 20:08
Description: Rendering screen

java.lang.NullPointerException
	at ayr.a(SourceFile:200)
	at ayi.b(SourceFile:382)
	at ayi.a(SourceFile:259)
	at ayq.a(SourceFile:122)
	at bii.b(SourceFile:844)
	at awp.aa(SourceFile:754)
	at awp.e(SourceFile:677)
	at net.minecraft.client.main.Main.main(SourceFile:104)


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

-- Head --
Stacktrace:
	at ayr.a(SourceFile:200)
	at ayi.b(SourceFile:382)
	at ayi.a(SourceFile:259)
	at ayq.a(SourceFile:122)

-- Screen render details --
Details:
	Screen name: ayq
	Mouse location: Scaled: (315, 334). Absolute: (630, 36)
	Screen size: Scaled: (683, 353). Absolute: (1366, 706). Scale factor of 2
Stacktrace:
	at bii.b(SourceFile:844)
	at awp.aa(SourceFile:754)
	at awp.e(SourceFile:677)
	at net.minecraft.client.main.Main.main(SourceFile:104)

-- System Details --
Details:
	Minecraft Version: 13w38c
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_21, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 270881976 bytes (258 MB) / 849346560 bytes (810 MB) up to 5726666752 bytes (5461 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx6G
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Launched Version: 13w38c
	LWJGL: 2.9.0
	OpenGL: ATI Mobility Radeon HD 5470  GL version 4.0.9836 Compatibility Profile Context, ATI Technologies Inc.
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Packs: []
	Current Language: English (UK)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: ~~ERROR~~ NullPointerException: null