[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]: java.util.ConcurrentModificationException
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at java.util.HashMap$HashIterator.nextNode(Unknown Source)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at java.util.HashMap$ValueIterator.next(Unknown Source)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75820_a(AnvilChunkLoader.java:367
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.world.chunk.storage.AnvilChunkLoader.func_75816_a(AnvilChunkLoader.java:197
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.world.gen.ChunkProviderServer.func_73242_b(ChunkProviderServer.java:256)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.world.gen.ChunkProviderServer.func_73156_b(ChunkProviderServer.java:343)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:165)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:625)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:334)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:547)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at fastcraft.c.p.a(F:19)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at fastcraft.Hooks.aq(F:153)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:396)
[19:33:42] [Server thread/INFO] [STDERR]: [java.lang.Throwable$WrappedPrintStream:println:-1]:  at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)