Description: Exception in server tick loop

ava.lang.IllegalArgumentException: n must be positive
	at java.util.Random.nextInt(Unknown Source)
	at alx.a(SourceFile:262)
	at alx.a(SourceFile:277)
	at alx.a(SourceFile:92)
	at alx.a(SourceFile:49)
	at alq.a(SourceFile:397)
	at amc.a(SourceFile:143)
	at azd.a(SourceFile:460)
	at od.a(SourceFile:175)
	at axw.a(SourceFile:859)
	at od.c(SourceFile:104)
	at net.minecraft.server.MinecraftServer.i(SourceFile:284)
	at cis.a(SourceFile:98)
	at cis.g(SourceFile:114)
	at net.minecraft.server.MinecraftServer.run(SourceFile:382)
	at mu.run(SourceFile:682)
...

http://paste.ee/p/9JKr7 <console log
http://pastebin.com/SzyLXiUs <Dump Log

Was using custom world gen w/ max everything except water level was at 64
lava lakes and lava rivers off