how come you crash????

--- Minecraft Crash Report ----
// Uh... Did I do that?

Time: 2/24/17 4:28 AM
Description: Exception in server tick loop

java.lang.IllegalArgumentException: Could not get provider type for dimension -112, does not exist
	at net.minecraftforge.common.DimensionManager.getProviderType(DimensionManager.java:148)
	at net.minecraftforge.common.DimensionManager.shouldLoadSpawn(DimensionManager.java:268)
	at net.minecraft.world.gen.ChunkProviderServer.func_73241_b(ChunkProviderServer.java:70)
	at net.minecraft.world.WorldServer.func_73044_a(WorldServer.java:820)
	at net.minecraft.server.MinecraftServer.func_71267_a(MinecraftServer.java:318)
	at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:106)
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427)
	at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)


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