Hopper: java.lang.IllegalArgumentException: n must be positive

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-145546/

Crash:

java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at aef.a(SourceFile:121)
	at aef.a(SourceFile:26)
	at adz.a(SourceFile:354)
	at agm.a(SourceFile:429)
	at kl.a(SourceFile:156)
	at afj.a(SourceFile:774)
	at kl.c(SourceFile:93)
	at kk.<init>(SourceFile:28)
	at kj.a(SourceFile:209)
	at kj.a(SourceFile:246)
	at jg.a(SourceFile:151)
	at jg.c(SourceFile:202)
	at jg.a(SourceFile:95)
	at boc.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.u(SourceFile:483)
	at net.minecraft.server.MinecraftServer.t(SourceFile:400)
	at bnz.t(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:334)
	at jb.run(SourceFile:577)

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

---- Minecraft Crash Report ----
// Hey, that tickles! Hehehe!

Time: 9/15/13 3:32 PM
Description: Exception in server tick loop

java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at aef.a(SourceFile:121)
	at aef.a(SourceFile:26)
	at adz.a(SourceFile:354)
	at agm.a(SourceFile:429)
	at kl.a(SourceFile:156)
	at afj.a(SourceFile:774)
	at kl.c(SourceFile:93)
	at kk.<init>(SourceFile:28)
	at kj.a(SourceFile:209)
	at kj.a(SourceFile:246)
	at jg.a(SourceFile:151)
	at jg.c(SourceFile:202)
	at jg.a(SourceFile:95)
	at boc.b(SourceFile:73)
	at net.minecraft.server.MinecraftServer.u(SourceFile:483)
	at net.minecraft.server.MinecraftServer.t(SourceFile:400)
	at bnz.t(SourceFile:124)
	at net.minecraft.server.MinecraftServer.run(SourceFile:334)
	at jb.run(SourceFile:577)


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

-- System Details --
Details:
	Minecraft Version: 13w37b
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 218378984 bytes (208 MB) / 332333056 bytes (316 MB) up to 3817799680 bytes (3640 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx4G
	AABB Pool Size: 1790 (100240 bytes; 0 MB) allocated, 1790 (100240 bytes; 0 MB) used
	IntCache: cache: 6, tcache: 68, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 1072 (60032 bytes; 0 MB) allocated, 1072 (60032 bytes; 0 MB) used
	Player Count: 1 / 8; [kp['deadbrainwaves'/147, l='PostA', x=-97.04, y=112.23, z=-48.90]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.

You can see this full report at http://hopper.minecraft.net/crashes/minecraft/MCX-145546/11077147/