Hopper: java.lang.NullPointerException: Invalid Biome id

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-772208/

Crash:

java.lang.NullPointerException: Invalid Biome id
	at agr.a(SourceFile:82)

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

---- Minecraft Crash Report ----
// I bet Cylons wouldn't have this problem.

Time: 12/5/13 3:45 PM
Description: Invalid Biome id

java.lang.NullPointerException: Invalid Biome id
	at agr.a(SourceFile:82)
	at agp.<init>(SourceFile:26)
	at ago.a(SourceFile:52)
	at ago.d(SourceFile:87)
	at agr.a(SourceFile:161)
	at agr.b(SourceFile:151)
	at app.d(SourceFile:194)
	at ml.c(SourceFile:78)
	at mk.<init>(SourceFile:32)
	at mj.a(SourceFile:212)
	at mj.a(SourceFile:249)
	at lg.a(SourceFile:155)
	at lg.c(SourceFile:206)
	at lg.a(SourceFile:100)
	at ng.c(SourceFile:87)
	at ng.a(SourceFile:52)
	at ef.a(SourceFile:166)
	at mv.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:528)
	at net.minecraft.server.MinecraftServer.t(SourceFile:440)
	at bti.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:357)
	at lb.run(SourceFile:616)


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

-- Head --
Stacktrace:
	at agr.a(SourceFile:82)

-- DownfallBlock --
Details:
	biome id: 0
	downfalls[] size: 256
	x: 16
	z: 352
	w: 16
	h: 16
Stacktrace:
	at agr.a(SourceFile:82)
	at agp.<init>(SourceFile:26)
	at ago.a(SourceFile:52)
	at ago.d(SourceFile:87)
	at agr.a(SourceFile:161)
	at agr.b(SourceFile:151)
	at app.d(SourceFile:194)

-- Chunk to be generated --
Details:
	Location: 1,22
	Position hash: 94489280513
	Generator: RandomLevelSource
Stacktrace:
	at ml.c(SourceFile:78)
	at mk.<init>(SourceFile:32)
	at mj.a(SourceFile:212)
	at mj.a(SourceFile:249)
	at lg.a(SourceFile:155)
	at lg.c(SourceFile:206)
	at lg.a(SourceFile:100)
	at ng.c(SourceFile:87)
	at ng.a(SourceFile:52)
	at ef.a(SourceFile:166)

-- Ticking connection --
Details:
	Connection: ef@3244eabe
Stacktrace:
	at mv.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:528)
	at net.minecraft.server.MinecraftServer.t(SourceFile:440)
	at bti.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:357)
	at lb.run(SourceFile:616)

-- System Details --
Details:
	Minecraft Version: 13w49a
	Operating System: Mac OS X (x86_64) version 10.9
	Java Version: 1.6.0_65, Apple Inc.
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Apple Inc.
	Memory: 94483864 bytes (90 MB) / 205017088 bytes (195 MB) up to 1060372480 bytes (1011 MB)
	JVM Flags: 1 total; -Xmx1G
	AABB Pool Size: 2989 (167384 bytes; 0 MB) allocated, 2980 (166880 bytes; 0 MB) used
	IntCache: cache: 7, tcache: 15, allocated: 14, tallocated: 123
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 529 (29624 bytes; 0 MB) allocated, 529 (29624 bytes; 0 MB) used
	Player Count: 1 / 8; [mp['olka95'/247, l='39a', x=-172.50, y=67.00, z=264.50]]
	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-772208/35810042/