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

java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at ajd.a(SourceFile:149)
	at ajd.a(SourceFile:73)
	at ns.c(SourceFile:142)

---- Minecraft Crash Report ----
// Uh... Did I do that?

Time: 06.02.14 15:44
Description: Exception ticking world

java.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at ajd.a(SourceFile:149)
	at ajd.a(SourceFile:73)
	at ns.c(SourceFile:142)
	at net.minecraft.server.MinecraftServer.v(SourceFile:519)
	at net.minecraft.server.MinecraftServer.u(SourceFile:461)
	at cbl.u(SourceFile:125)
	at net.minecraft.server.MinecraftServer.run(SourceFile:377)
	at mi.run(SourceFile:647)


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

-- Head --
Stacktrace:
	at java.util.Random.nextInt(Unknown Source)
	at ajd.a(SourceFile:149)
	at ajd.a(SourceFile:73)
	at ns.c(SourceFile:142)

-- Affected level --
Details:
	Level name: 1.9 prerelase
	All players: 1 total; [nv['Antyradek'/148, l='1.9 prerelase', x=-23,00, y=83,50, z=26,00]]
	Chunk stats: ServerChunkCache: 225 Drop: 0
	Level seed: -2067431225
	Level generator: ID 00 - default, ver 1. Features enabled: false
	Level generator options: 
	Level spawn location: 0,00,0,00,0,00 - World: (0,0,0), Chunk: (at 0,0,0 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
	Level time: 0 game time, 0 day time
	Level dimension: 0
	Level storage version: 0x00000 - Unknown?
	Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
	Level game mode: ~~ERROR~~ NullPointerException: null
Stacktrace:
	at net.minecraft.server.MinecraftServer.v(SourceFile:519)
	at net.minecraft.server.MinecraftServer.u(SourceFile:461)
	at cbl.u(SourceFile:125)
	at net.minecraft.server.MinecraftServer.run(SourceFile:377)
	at mi.run(SourceFile:647)

-- System Details --
Details:
	Minecraft Version: 14w06a
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_02, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 128757416 bytes (122 MB) / 264044544 bytes (251 MB) up to 954466304 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [nv['Antyradek'/148, l='1.9 prerelase', x=-23,00, y=83,50, z=26,00]]
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.