Problem Monster 1.0.3 console spam

[bojangels19]

My console keeps getting spammed with these lines and I'm not sure what's causing it.

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Spoiler

3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] java.util.ConcurrentModificationException
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at java.util.HashMap$ValueIterator.next(Unknown Source)
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at net.minecraft.nbt.NBTTagCompound.func_74734_a(SourceFile:25)
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at net.minecraft.nbt.NBTBase.func_74731_a(SourceFile:119)
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at net.minecraft.nbt.CompressedStreamTools.func_74800_a(CompressedStreamTools.java:140)
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75821_a(AnvilChunkLoader.java:198)
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75814_c(AnvilChunkLoader.java:184)
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at net.minecraft.world.storage.ThreadedFileIOBase.func_75736_b(SourceFile:30)
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at net.minecraft.world.storage.ThreadedFileIOBase.run(SourceFile:23)
‎3‎:‎22‎:‎19‎ ‎AM
CONSOLE:
[INFO] at java.lang.Thread.run(Unknown Source)