[ExtraHardMode] Task #48 for ExtraHardMode v3.6.4 generated an exception
java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429) ~[?:1.8.0_25]
        at java.util.HashMap$KeyIterator.next(HashMap.java:1453) ~[?:1.8.0_25]
        at com.extrahardmode.task.WeightCheckTask.run(WeightCheckTask.java:37) ~[?:?]
        at org.bukkit.craftbukkit.v1_8_R1.scheduler.CraftTask.run(CraftTask.java:71) ~[survival.jar:git-Spigot-15fa8e1-17a3db7]
        at org.bukkit.craftbukkit.v1_8_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:350) [survival.jar:git-Spigot-15fa8e1-17a3db7]
        at net.minecraft.server.v1_8_R1.MinecraftServer.z(MinecraftServer.java:709) [survival.jar:git-Spigot-15fa8e1-17a3db7]
        at net.minecraft.server.v1_8_R1.DedicatedServer.z(DedicatedServer.java:316) [survival.jar:git-Spigot-15fa8e1-17a3db7]
        at net.minecraft.server.v1_8_R1.MinecraftServer.y(MinecraftServer.java:634) [survival.jar:git-Spigot-15fa8e1-17a3db7]
        at net.minecraft.server.v1_8_R1.MinecraftServer.run(MinecraftServer.java:537) [survival.jar:git-Spigot-15fa8e1-17a3db7]