Crash jukebox

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

Time: 01.12.2012 16:05
Description: Ticking memory connection

java.lang.NullPointerException
	at um.f(SourceFile:129)
	at um.h(SourceFile:143)
	at qw.a(SourceFile:219)
	at px.c_(SourceFile:178)
	at qx.r(SourceFile:388)
	at qx.c(SourceFile:380)
	at md.j_(SourceFile:526)
	at qx.j_(SourceFile:200)
	at iq.g(SourceFile:175)
	at iv.a(SourceFile:199)
	at ec.a(SourceFile:136)
	at cf.b(SourceFile:55)
	at iv.d(SourceFile:57)
	at iw.b(SourceFile:39)
	at bdr.b(SourceFile:84)
	at net.minecraft.server.MinecraftServer.r(SourceFile:769)
	at net.minecraft.server.MinecraftServer.q(SourceFile:686)
	at bdo.q(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:620)
	at fy.run(SourceFile:856)


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

-- System Details --
Details:
	Minecraft Version: 1.4.5
	Operating System: Mac OS X (i386) version 10.8.2
	Java Version: 1.6.0_37, Apple Inc.
	Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Apple Inc.
	Memory: 141769336 bytes (135 MB) / 587005952 bytes (559 MB) up to 1060372480 bytes (1011 MB)
	JVM Flags: 3 total; -Xbootclasspath/a:/System/Library/PrivateFrameworks/JavaApplicationLauncher.framework/Resources/LauncherSupport.jar -Xms512M -Xmx1024M
	AABB Pool Size: 1721 (96376 bytes; 0 MB) allocated, 1539 (86184 bytes; 0 MB) used
	Suspicious classes: _tmi_MgButtonHandler, _tmi_MgItemHandler, _tmi_MgFocusHandler, ...]
	IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 206 (11536 bytes; 0 MB) allocated, 169 (9464 bytes; 0 MB) used
	Player Count: 1 / 8; [iq['can'/142, l='SURV‹VAL', x=276,32, y=4,56, z=965,35]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Very likely; Jar signature invalidated