Hopper: java.lang.NullPointerException

This is an automatically generated report based from the following crash: http://hopper.minecraft.net/crashes/minecraft/MCX-293807/

Crash:

java.lang.NullPointerException
	at agi.a(SourceFile:82)

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

---- Minecraft Crash Report ----
// Sorry :(

Time: 10.10.2013 18:10
Description: Invalid Biome id

java.lang.NullPointerException
	at agi.a(SourceFile:82)
	at agg.<init>(SourceFile:26)
	at agf.a(SourceFile:52)
	at agf.d(SourceFile:87)
	at agi.a(SourceFile:160)
	at agi.b(SourceFile:150)
	at apa.d(SourceFile:194)
	at me.c(SourceFile:78)
	at me.d(SourceFile:108)
	at afh.e(SourceFile:310)
	at afh.a(SourceFile:248)
	at afv.b(SourceFile:85)
	at afv.a(SourceFile:50)
	at lb.a(SourceFile:442)
	at lb.a(SourceFile:372)
	at mi.b(SourceFile:362)
	at qh.C(SourceFile:331)
	at rb.C(SourceFile:168)
	at qh.h(SourceFile:294)
	at rb.h(SourceFile:1169)
	at xf.h(SourceFile:240)
	at mi.i(SourceFile:207)
	at ms.a(SourceFile:201)
	at is.a(SourceFile:127)
	at is.a(SourceFile:8)
	at ek.a(SourceFile:150)
	at mo.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:528)
	at net.minecraft.server.MinecraftServer.t(SourceFile:440)
	at brh.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kw.run(SourceFile:616)


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

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

-- DownfallBlock --
Details:
	downfalls[] size: 256
	x: 1952
	z: 752
	w: 16
	h: 16
Stacktrace:
	at agi.a(SourceFile:82)
	at agg.<init>(SourceFile:26)
	at agf.a(SourceFile:52)
	at agf.d(SourceFile:87)
	at agi.a(SourceFile:160)
	at agi.b(SourceFile:150)
	at apa.d(SourceFile:194)

-- Chunk to be generated --
Details:
	Location: 122,47
	Position hash: 201863463034
	Generator: RandomLevelSource
Stacktrace:
	at me.c(SourceFile:78)
	at me.d(SourceFile:108)
	at afh.e(SourceFile:310)

-- Requested block coordinates --
Details:
	Found chunk: true
	Location: World: (1952,255,752), Chunk: (at 0,15,0 in 122,47; contains blocks 1952,0,752 to 1967,255,767), Region: (3,1; contains chunks 96,32 to 127,63, blocks 1536,0,512 to 2047,255,1023)
Stacktrace:
	at afh.a(SourceFile:248)
	at afv.b(SourceFile:85)
	at afv.a(SourceFile:50)
	at lb.a(SourceFile:442)
	at lb.a(SourceFile:372)
	at mi.b(SourceFile:362)
	at qh.C(SourceFile:331)
	at rb.C(SourceFile:168)
	at qh.h(SourceFile:294)
	at rb.h(SourceFile:1169)
	at xf.h(SourceFile:240)

-- Player being ticked --
Details:
	Entity Type: null (mi)
	Entity ID: 287
	Entity Name: jpumc
	Entity's Exact location: 2075,00, 37,00, 677,00
	Entity's Block location: World: (2075,37,677), Chunk: (at 11,2,5 in 129,42; contains blocks 2064,0,672 to 2079,255,687), Region: (4,1; contains chunks 128,32 to 159,63, blocks 2048,0,512 to 2559,255,1023)
	Entity's Momentum: 0,00, -0,08, 0,00
Stacktrace:
	at mi.i(SourceFile:207)
	at ms.a(SourceFile:201)
	at is.a(SourceFile:127)
	at is.a(SourceFile:8)
	at ek.a(SourceFile:150)

-- Ticking connection --
Details:
	Connection: ek@7deb98f6
Stacktrace:
	at mo.c(SourceFile:134)
	at net.minecraft.server.MinecraftServer.u(SourceFile:528)
	at net.minecraft.server.MinecraftServer.t(SourceFile:440)
	at brh.t(SourceFile:117)
	at net.minecraft.server.MinecraftServer.run(SourceFile:358)
	at kw.run(SourceFile:616)

-- System Details --
Details:
	Minecraft Version: 13w41a
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_40, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 365302128 bytes (348 MB) / 528482304 bytes (504 MB) up to 954728448 bytes (910 MB)
	JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
	AABB Pool Size: 164 (9184 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	IntCache: cache: 1, tcache: 23, allocated: 13, tallocated: 95
	Profiler Position: N/A (disabled)
	Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
	Player Count: 1 / 8; [mi['jpumc'/287, l='Snap', x=2075,00, y=37,00, z=677,00]]
	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-293807/16540267/