Description: Exception in server tick loop

java.lang.NullPointerException: Exception in server tick loop
	at net.cyberninjapiggy.apocalyptic.generator.RavagedChunkGenerator.getDefaultPopulators(RavagedChunkGenerator.java:233)
	at net.minecraft.server.v1_7_R1.MinecraftServer.a(MinecraftServer.java:259)
	at net.minecraft.server.v1_7_R1.DedicatedServer.init(DedicatedServer.java:175)
	at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:424)
	at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617)