I walked outside my house and a skeleton shot an arrow and the arrow hit a fence. I opened my gate and walked outside. As I went to attack the skeleton my game froze and it gave me a crash message(below). I don't have any mods installed whatsoever. The world I was playing in was created before 1.4.6 so it might have something to do with that but I don't know.

Error report:

Minecraft has crashed!
----------------------

Minecraft has stopped running because it encountered a problem; Ticking entity

A full error report has been saved to /Users/DanielSeguin/Library/Application Support/minecraft/crash-reports/crash-2012-12-17_12.33.44-server.txt - Please include a copy of that file (Not this screen!) if you report this crash to anyone; without it, they will not be able to help fix the crash

— BEGIN ERROR REPORT 64c6ccc1 --------
Full report at:
/Users/DanielSeguin/Library/Application Support/minecraft/crash-reports/crash-2012-12-17_12.33.44-server.txt
Please show that file to Mojang, NOT just this screen!

Generated 12/17/12 12:33 PM

– Head –
Stacktrace:
at qz.j_(SourceFile:276)
at yc.a(SourceFile:1319)
at in.a(SourceFile:450)
at yc.g(SourceFile:1297)

– Entity being ticked –
Details:
Entity Type: Arrow (qz)
Entity ID: 260546
Name: arrow
Exact location: 23.94, 65.34, 260.25
Block location: World: (23,65,260), Chunk: (at 7,4,4 in 1,16; contains blocks 16,0,256 to 31,255,271), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Momentum: 1.60, -0.58, 0.08
Stacktrace:
at yc.h(SourceFile:1196)
at in.h(SourceFile:362)

– Affected level –
Details:
Level name: My Town
All players: 1 total; [iq['DaBoy9123'/225890, l='My Town', x=25.72, y=63.00, z=260.38]]
Chunk stats: ServerChunkCache: 605 Drop: 0
Level seed: 72726
Level generator: ID 00 - default, ver 1. Features enabled: true
Level generator options:
Level spawn location: World: (0,64,244), Chunk: (at 0,4,4 in 0,15; contains blocks 0,0,240 to 15,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
Level time: 2904059 game time, 3092806 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 147118 (now: false), thunder time: 2400 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
at net.minecraft.server.MinecraftServer.r(SourceFile:744)
at net.minecraft.server.MinecraftServer.q(SourceFile:679)
at bdz.q(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:613)
at fy.run(SourceFile:849)

– System Details –
Details:
Minecraft Version: 1.4.6
Operating System: Mac OS X (x86_64) version 10.8.2
Java Version: 1.6.0_37, Apple Inc.
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
Memory: 410532632 bytes (391 MB) / 581435392 bytes (554 MB) up to 1065025536 bytes (1015 MB)
JVM Flags: 3 total; -Xbootclasspath/a:/System/Library/PrivateFrameworks/JavaApplicationLauncher.framework/Resources/LauncherSupport.jar -Xms512M -Xmx1024M
AABB Pool Size: 4516 (252896 bytes; 0 MB) allocated, 3803 (212968 bytes; 0 MB) used
Suspicious classes: No suspicious classes found.
IntCache: cache: 0, tcache: 0, allocated: 3, tallocated: 63
Profiler Position: N/A (disabled)
Vec3 Pool Size: 1318 (73808 bytes; 0 MB) allocated, 1095 (61320 bytes; 0 MB) used
Player Count: 1 / 8; [iq['DaBoy9123'/225890, l='My Town', x=25.72, y=63.00, z=260.38]]
Type: Integrated Server (map_client.txt)
Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

java.lang.ClassCastException: qn cannot be cast to iq
at qz.j_(SourceFile:276)
at yc.a(SourceFile:1319)
at in.a(SourceFile:450)
at yc.g(SourceFile:1297)
at yc.h(SourceFile:1196)
at in.h(SourceFile:362)
at net.minecraft.server.MinecraftServer.r(SourceFile:744)
at net.minecraft.server.MinecraftServer.q(SourceFile:679)
at bdz.q(SourceFile:117)
at net.minecraft.server.MinecraftServer.run(SourceFile:613)
at fy.run(SourceFile:849)
— END ERROR REPORT 63685640 ----------