java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:926)
at java.util.HashMap$KeyIterator.next(HashMap.java:960)
at net.minecraft.entity.EntityTracker.func_72788_a(EntityTracker.java:271)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:978)
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:431)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:809)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:669)
at java.lang.Thread.run(Thread.java:744)

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