Hopper: java.lang.NullPointerException bct.a(SourceFile:571)

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-14518/

Crash:

java.lang.NullPointerException
	at bct.a(SourceFile:571)
	at df.a(SourceFile:87)
	at cn.b(SourceFile:354)
	at bct.e(SourceFile:98)
	at bdh.c(SourceFile:31)

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

---- Minecraft Crash Report ----
// My bad.

Time: 8/15/13 9:29 PM
Description: Ticking screen

java.lang.NullPointerException
	at bct.a(SourceFile:571)
	at df.a(SourceFile:87)
	at cn.b(SourceFile:354)
	at bct.e(SourceFile:98)
	at bdh.c(SourceFile:31)
	at ats.k(SourceFile:1173)
	at ats.S(SourceFile:663)
	at ats.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)


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

-- Head --
Stacktrace:
	at bct.a(SourceFile:571)
	at df.a(SourceFile:87)
	at cn.b(SourceFile:354)
	at bct.e(SourceFile:98)
	at bdh.c(SourceFile:31)

-- Affected screen --
Details:
	Screen name: ~~ERROR~~ NullPointerException: null

-- Affected level --
Details:
	Level name: MpServer
	All players: 1 total; [bdf['aerogolioth'/2742432, l='MpServer', x=607.50, y=65.62, z=-598.50]]
	Chunk stats: MultiplayerChunkCache: 5
	Level seed: 0
	Level generator: ID 01 - flat, ver 0. Features enabled: false
	Level generator options: 
	Level spawn location: World: (614,4,-605), Chunk: (at 6,0,3 in 38,-38; contains blocks 608,0,-608 to 623,255,-593), Region: (1,-2; contains chunks 32,-64 to 63,-33, blocks 512,0,-1024 to 1023,255,-513)
	Level time: 209041 game time, 219040 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: Game mode: survival (ID 0). Hardcore: false. Cheats: false
	Forced entities: 1 total; [bdf['aerogolioth'/2742432, l='MpServer', x=607.50, y=65.62, z=-598.50]]
	Retry entities: 0 total; []
	Server brand: vanilla
	Server type: Non-integrated multiplayer server
Stacktrace:
	at bda.a(SourceFile:284)
	at ats.b(SourceFile:1761)
	at ats.d(SourceFile:628)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.2
	Operating System: Windows 7 (x86) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode, sharing), Oracle Corporation
	Memory: 40378200 bytes (38 MB) / 83333120 bytes (79 MB) up to 518979584 bytes (494 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M
	AABB Pool Size: 7955 (445480 bytes; 0 MB) allocated, 2 (112 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Launched Version: modloader
	LWJGL: 2.9.0
	OpenGL: Intel(R) HD Graphics GL version 2.1.0 - Build 8.15.10.2202, Intel
	Is Modded: Probably not. Jar signature remains and client brand is untouched.
	Type: Client (map_client.txt)
	Resource Pack: Default
	Current Language: English (US)
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 148 (8288 bytes; 0 MB) allocated, 10 (560 bytes; 0 MB) used

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-14518/3253445/