Whenever I start or create a new world with the generator. after enabling structures I get:

Description: Exception generating new chunk

java.lang.NullPointerException
at com.github.barteks2x.b173gen.reflection.WorldGenBaseRef.generate(WorldGenBaseRef.java:31)
at com.github.barteks2x.b173gen.generator.ChunkProviderGenerate.generateBlockSections(ChunkProviderGenerate.java:236)
at org.bukkit.craftbukkit.v1_6_R2.generator.CustomChunkGenerator.getOrCreateChunk(CustomChunkGenerator.java:98)
at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:111)
at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:84)
at net.minecraft.server.v1_6_R2.ChunkProviderServer.getOrCreateChunk(ChunkProviderServer.java:158)
at net.minecraft.server.v1_6_R2.World.getChunkAt(World.java:277)
at net.minecraft.server.v1_6_R2.World.getTypeId(World.java:202)
at org.bukkit.craftbukkit.v1_6_R2.CraftWorld.getBlockTypeIdAt(CraftWorld.java:87)
at com.github.barteks2x.b173gen.generator.ChunkProviderGenerate.canSpawn(ChunkProviderGenerate.java:740)
at com.github.barteks2x.b173gen.generator.ChunkProviderGenerate.getFixedSpawnLocation(ChunkProviderGenerate.java:752)
at net.minecraft.server.v1_6_R2.WorldServer.b(WorldServer.java:700)
at net.minecraft.server.v1_6_R2.WorldServer.a(WorldServer.java:680)
at net.minecraft.server.v1_6_R2.World.(World.java:144)
at net.minecraft.server.v1_6_R2.WorldServer.(WorldServer.java:46)
at net.minecraft.server.v1_6_R2.MinecraftServer.a(MinecraftServer.java:190)
at net.minecraft.server.v1_6_R2.DedicatedServer.init(DedicatedServer.java:151)
at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:391)
at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)

Fixed in build #39.

---- Minecraft Crash Report ----
// I'm sorry, Dave.

Time: 07/08/13 7:32 PM
Description: Exception generating new chunk

java.lang.NullPointerException
at com.github.barteks2x.b173gen.reflection.WorldGenBaseRef.generate(WorldGenBaseRef.java:32)
at com.github.barteks2x.b173gen.generator.ChunkProviderGenerate.generateBlockSections(ChunkProviderGenerate.java:230)
at org.bukkit.craftbukkit.v1_6_R2.generator.CustomChunkGenerator.getOrCreateChunk(CustomChunkGenerator.java:98)
at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:111)
at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:84)
at net.minecraft.server.v1_6_R2.ChunkProviderServer.getOrCreateChunk(ChunkProviderServer.java:158)
at net.minecraft.server.v1_6_R2.World.getChunkAt(World.java:277)
at net.minecraft.server.v1_6_R2.World.getTypeId(World.java:202)
at org.bukkit.craftbukkit.v1_6_R2.CraftWorld.getBlockTypeIdAt(CraftWorld.java:86)
at com.github.barteks2x.b173gen.generator.ChunkProviderGenerate.canSpawn(ChunkProviderGenerate.java:740)
at com.github.barteks2x.b173gen.generator.ChunkProviderGenerate.getFixedSpawnLocation(ChunkProviderGenerate.java:752)
at net.minecraft.server.v1_6_R2.WorldServer.b(WorldServer.java:700)
at net.minecraft.server.v1_6_R2.WorldServer.a(WorldServer.java:680)
at net.minecraft.server.v1_6_R2.World.(World.java:144)
at net.minecraft.server.v1_6_R2.WorldServer.(WorldServer.java:46)
at net.minecraft.server.v1_6_R2.MinecraftServer.a(MinecraftServer.java:190)
at net.minecraft.server.v1_6_R2.DedicatedServer.init(DedicatedServer.java:151)
at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:391)
at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)

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

-- Head --
Stacktrace:
at com.github.barteks2x.b173gen.reflection.WorldGenBaseRef.generate(WorldGenBaseRef.java:32)
at com.github.barteks2x.b173gen.generator.ChunkProviderGenerate.generateBlockSections(ChunkProviderGenerate.java:230)
at org.bukkit.craftbukkit.v1_6_R2.generator.CustomChunkGenerator.getOrCreateChunk(CustomChunkGenerator.java:98)

-- Chunk to be generated --
Details:
Location: 0,0
Position hash: 2147483648
Generator: CustomChunkGenerator
Stacktrace:
at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:111)
at net.minecraft.server.v1_6_R2.ChunkProviderServer.getChunkAt(ChunkProviderServer.java:84)
at net.minecraft.server.v1_6_R2.ChunkProviderServer.getOrCreateChunk(ChunkProviderServer.java:158)
at net.minecraft.server.v1_6_R2.World.getChunkAt(World.java:277)

-- Requested block coordinates --
Details:
Found chunk: true
Location: World: (0,64,0), Chunk: (at 0,4,0 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)
Stacktrace:
at net.minecraft.server.v1_6_R2.World.getTypeId(World.java:202)
at org.bukkit.craftbukkit.v1_6_R2.CraftWorld.getBlockTypeIdAt(CraftWorld.java:86)
at com.github.barteks2x.b173gen.generator.ChunkProviderGenerate.canSpawn(ChunkProviderGenerate.java:740)
at com.github.barteks2x.b173gen.generator.ChunkProviderGenerate.getFixedSpawnLocation(ChunkProviderGenerate.java:752)
at net.minecraft.server.v1_6_R2.WorldServer.b(WorldServer.java:700)
at net.minecraft.server.v1_6_R2.WorldServer.a(WorldServer.java:680)

-- Affected level --
Details:
Level name: world
All players: 0 total; []
Chunk stats: ServerChunkCache: 0 Drop: 0
Level seed: 1772835215
Level generator: ID 00 - default, ver 1. 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: 0x00000 - Unknown?
Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
at net.minecraft.server.v1_6_R2.World.(World.java:144)
at net.minecraft.server.v1_6_R2.WorldServer.(WorldServer.java:46)
at net.minecraft.server.v1_6_R2.MinecraftServer.a(MinecraftServer.java:190)
at net.minecraft.server.v1_6_R2.DedicatedServer.init(DedicatedServer.java:151)
at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:391)
at net.minecraft.server.v1_6_R2.ThreadServerApplication.run(SourceFile:582)

===Config===
structures:
canyons: false
strongholds: true
villages: true
temples: true
mineshafts: false
newFeatures:
newCaves: false
newClayGenerator: false
newLakeGenerator: false
newDungeonGenerator: true
ores:
emeralds: true
other:
oldTreeGrowing: true
messages:
eyeOfEnderMsg: You can't use Eye of Ender in this world!

Fixed.