Crash

I was in minecraft and left my computer idol. I tried to log off of the game and I came back to it later and this was on the screen.

---- Minecraft Crash Report ----
// There are four lights!

Time: 6/21/14 5:26 PM
Description: Exception in server tick loop

java.lang.ArrayIndexOutOfBoundsException: -1
	at java.util.ArrayList.fastRemove(ArrayList.java:441)
	at java.util.ArrayList.remove(ArrayList.java:424)
	at os.b(SourceFile:62)
	at or.c(SourceFile:328)
	at qh.e(SourceFile:302)
	at ph.a(SourceFile:530)
	at pc.c(SourceFile:131)
	at net.minecraft.server.MinecraftServer.w(SourceFile:596)
	at net.minecraft.server.MinecraftServer.v(SourceFile:506)
	at coe.v(SourceFile:132)
	at net.minecraft.server.MinecraftServer.run(SourceFile:422)
	at java.lang.Thread.run(Thread.java:695)


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
	Minecraft Version: 14w25b
	Operating System: Mac OS X (x86_64) version 10.9.3
	Java Version: 1.6.0_65, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 174573360 bytes (166 MB) / 506081280 bytes (482 MB) up to 1065025536 bytes (1015 MB)
	JVM Flags: 1 total; -Xmx1G
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [ox['averyasher'/269, l='world', x=-411.83, y=113.39, z=-663.57]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.