---- Minecraft Crash Report ----
// This doesn't make any sense!

Time: 10/31/15 8:34 AM
Description: Exception in server tick loop

java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextEntry(HashMap.java:922)
        at java.util.HashMap$KeyIterator.next(HashMap.java:956)
        at ln.a(SourceFile:180)
        at net.minecraft.server.MinecraftServer.D(SourceFile:626)
        at lb.D(SourceFile:314)
        at net.minecraft.server.MinecraftServer.C(SourceFile:546)
        at net.minecraft.server.MinecraftServer.run(SourceFile:450)
        at java.lang.Thread.run(Thread.java:745)


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

-- System Details --
Details:
        Minecraft Version: 15w44b
        Operating System: Linux (amd64) version 3.2.0-4-amd64
        Java Version: 1.7.0_79, Oracle Corporation
        Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
        Memory: 155584320 bytes (148 MB) / 339996672 bytes (324 MB) up to 989331456 bytes (943 MB)
        JVM Flags: 1 total; -XX:MaxPermSize=1G
        IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
        Profiler Position: N/A (disabled)
        Player Count: 1 / 4; [ls['NicoLeRigolo'/173, l='juco', x=206.29, y=99.52, z=25.68]]
        Is Modded: Unknown (can't tell)
        Type: Dedicated Server (map_server.txt)