i am getting this crash while trying to play bears den.
---- Minecraft Crash Report ----
// Hey, that tickles! Hehehe!
Time: 1/22/17 5:20 PM
Description: Exception in server tick loop
java.lang.NullPointerException: Exception in server tick loop
at net.minecraft.world.chunk.storage.ExtendedBlockStorage.func_150818_a(SourceFile:57)
at net.minecraft.world.chunk.Chunk.func_150807_a(Chunk.java:595)
at net.minecraft.world.World.func_147465_d(World.java:451)
at ihl.worldgen.WorldGenLiquidOre.func_76484_a(WorldGenLiquidOre.java:26)
at ihl.worldgen.IHLWorldGenerator.generate(IHLWorldGenerator.java:106)
at cpw.mods.fml.common.registry.GameRegistry.generateWorld(GameRegistry.java:112)
at net.minecraft.world.gen.ChunkProviderServer.func_73153_a(ChunkProviderServer.java:280)
at net.minecraft.world.chunk.Chunk.func_76624_a(Chunk.java:1045)
at net.minecraftforge.common.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:52)
at net.minecraftforge.common.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:12)
at net.minecraftforge.common.util.AsynchronousExecutor$Task.finish(AsynchronousExecutor.java:189)
at net.minecraftforge.common.util.AsynchronousExecutor.finishActive(AsynchronousExecutor.java:354)
at net.minecraftforge.common.chunkio.ChunkIOExecutor.tick(ChunkIOExecutor.java:30)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:596)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:547)
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:111)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:396)
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)
Trying to enter this custom pack with seed as "Grag" dont even start. Looks promising.