I get this crash log when trying to generate my custom world type:

---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 6/12/14 3:09 PM
Description: Exception initializing level

java.lang.NullPointerException: Exception initializing level
at net.minecraft.world.biome.WorldChunkManager.findBiomePosition(WorldChunkManager.java:250)
at net.minecraft.world.WorldServer.createSpawnPosition(WorldServer.java:789)
at net.minecraft.world.WorldServer.initialize(WorldServer.java:770)
at net.minecraft.world.World.<init>(World.java:301)
at net.minecraft.world.WorldServer.<init>(WorldServer.java:103)
at net.minecraft.server.integrated.IntegratedServer.loadAllWorlds(IntegratedServer.java:63)
at net.minecraft.server.integrated.IntegratedServer.startServer(IntegratedServer.java:96)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:442)
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:746)


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

-- Head --
Stacktrace:
at net.minecraft.world.biome.WorldChunkManager.findBiomePosition(WorldChunkManager.java:250)
at net.minecraft.world.WorldServer.createSpawnPosition(WorldServer.java:789)
at net.minecraft.world.WorldServer.initialize(WorldServer.java:770)

-- Affected level --
Details:
Level name: New World
All players: 0 total; []
Chunk stats: ServerChunkCache: 0 Drop: 0
Level seed: 6065247161752847507
Level generator: ID 04 - UNDEAD_OUTLAST, ver 0. Features enabled: true
Level generator options: 
Level spawn location: 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: 0x04ABD - Anvil
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true
Stacktrace:
at net.minecraft.world.World.<init>(World.java:301)
at net.minecraft.world.WorldServer.<init>(WorldServer.java:103)
at net.minecraft.server.integrated.IntegratedServer.loadAllWorlds(IntegratedServer.java:63)
at net.minecraft.server.integrated.IntegratedServer.startServer(IntegratedServer.java:96)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:442)
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:746)

-- System Details --
Details:
Minecraft Version: 1.7.2
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 929456488 bytes (886 MB) / 1038876672 bytes (990 MB) up to 1038876672 bytes (990 MB)
JVM Flags: 3 total; -Xincgc -Xmx1024M -Xms1024M
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP v9.03 FML v7.2.196.1084 Minecraft Forge 10.12.1.1084 11 mods loaded, 11 mods active
mcp{9.03} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
FML{7.2.196.1084} [Forge Mod Loader] (forgeSrc-1.7.2-10.12.1.1084.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
Forge{10.12.1.1084} [Minecraft Forge] (forgeSrc-1.7.2-10.12.1.1084.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
enderrepositories{1.2} [Ender Repositories] (bin) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
fans{1.1} [Fans] (bin) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
flappyworld{1.2} [Flappy World] (bin) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
legions{1.0} [Legions] (bin) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
realmoffera{1.0} [Realm of Fera] (bin) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
undeadoutlast{1.0} [undead Outlast] (bin) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
tlhpoeCore{1.3} [TLHPoE Core] (bin) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
tlhtweaks{1.0} [TLH Tweaks] (bin) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available
Profiler Position: N/A (disabled)
Player Count: 0 / 8; []
Type: Integrated Server (map_client.txt)
Is Modded: Definitely; Client brand changed to 'fml,forge'

 

WorldTypeUndeadOutlast:

package undeadoutlast.world;

import cpw.mods.fml.relauncher.Side;
import cpw.mods.fml.relauncher.SideOnly;
import net.minecraft.world.World;
import net.minecraft.world.WorldType;
import net.minecraft.world.biome.WorldChunkManager;
import net.minecraft.world.chunk.IChunkProvider;

public class WorldTypeUndeadOutlast extends WorldType {
public WorldTypeUndeadOutlast() {
	super("UNDEAD_OUTLAST");
}

@Override
public WorldChunkManager getChunkManager(World world) {
	return new WorldChunkManagerOU();
}

@Override
public IChunkProvider getChunkGenerator(World world, String generatorOptions) {
	return new ChunkProviderOU(world, world.getSeed(), world.getWorldInfo().isMapFeaturesEnabled());
}

@Override
public int getSpawnFuzz() {
	return 100;
}

@Override
@SideOnly(Side.CLIENT)
public boolean showWorldInfoNotice() {
	return true;
}
}

 

WorldChunkManagerOU:

package undeadoutlast.world;

import java.util.List;
import java.util.Random;

import net.minecraft.world.ChunkPosition;
import net.minecraft.world.biome.BiomeGenBase;
import net.minecraft.world.biome.WorldChunkManager;
import undeadoutlast.ServerProxy;

public class WorldChunkManagerOU extends WorldChunkManager {
public WorldChunkManagerOU() {
	super();
}
}

 

ChunkProviderOU:

package undeadoutlast.world;

import net.minecraft.world.World;
import net.minecraft.world.gen.ChunkProviderEnd;
import net.minecraft.world.gen.ChunkProviderGenerate;

public class ChunkProviderOU extends ChunkProviderGenerate {
public ChunkProviderOU(World par1World, long par2, boolean par3) {
	super(par1World, par2, par3);
}
}

Anything?