Hopper: java.lang.NullPointerException

java.lang.NullPointerException
	at acd.<init>(SourceFile:90)
	at atv.a(SourceFile:1426)
	at awh.e(SourceFile:157)
	at awi.a(SourceFile:210)
	at awg.a(SourceFile:173)
	at awh.a(SourceFile:183)

---- Minecraft Crash Report ----
// This is a token for 1 free hug. Redeem at your nearest Mojangsta: [~~HUG~~]

Time: 9/20/13 3:28 PM
Description: Rendering screen

java.lang.NullPointerException
	at acd.<init>(SourceFile:90)
	at atv.a(SourceFile:1426)
	at awh.e(SourceFile:157)
	at awi.a(SourceFile:210)
	at awg.a(SourceFile:173)
	at awh.a(SourceFile:183)
	at bfe.b(SourceFile:718)
	at atv.S(SourceFile:686)
	at atv.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 acd.<init>(SourceFile:90)
	at atv.a(SourceFile:1426)
	at awh.e(SourceFile:157)
	at awi.a(SourceFile:210)
	at awg.a(SourceFile:173)
	at awh.a(SourceFile:183)

-- Screen render details --
Details:
	Screen name: blt
	Mouse location: Scaled: (211, 61). Absolute: (423, 356)
	Screen size: Scaled: (427, 240). Absolute: (854, 480). Scale factor of 2
Stacktrace:
	at bfe.b(SourceFile:718)
	at atv.S(SourceFile:686)
	at atv.d(SourceFile:619)
	at net.minecraft.client.main.Main.main(SourceFile:101)

-- System Details --
Details:
	Minecraft Version: 1.6.4
	Operating System: Mac OS X (x86_64) version 10.7.5
	Java Version: 1.6.0_45, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 166028776 bytes (158 MB) / 330502144 bytes (315 MB) up to 1069416448 bytes (1019 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Suspicious classes: No suspicious classes found.
	IntCache: cache: 0, tcache: 0, allocated: 1, tallocated: 63
	Launched Version: 1.6.4
	LWJGL: 2.9.0
	OpenGL: ATI Radeon X1600 OpenGL Engine GL version 2.1 ATI-7.4.1, ATI Technologies Inc.
	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: ~~ERROR~~ NullPointerException: null