Bending Crash

[18:20:36] [Server thread/WARN]: [JedCore] Task #50 for JedCore v1.1.4 generated an exception
java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:819) ~[?:1.7.0_21]
	at java.util.ArrayList$Itr.next(ArrayList.java:791) ~[?:1.7.0_21]
	at com.jedk1.JedCore.combos.WaterFlow.manageLength(WaterFlow.java:139) ~[?:?]
	at com.jedk1.JedCore.combos.WaterFlow.progress(WaterFlow.java:132) ~[?:?]
	at com.jedk1.JedCore.combos.WaterFlow.progressAll(WaterFlow.java:255) ~[?:?]
	at com.jedk1.JedCore.waterbending.WaterbendingManager.run(WaterbendingManager.java:29) ~[?:?]
	at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftTask.run(CraftTask.java:71) ~[spigot-1.8.7.jar:git-Spigot-f928e7a-f27339c]
	at org.bukkit.craftbukkit.v1_8_R3.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:350) [spigot-1.8.7.jar:git-Spigot-f928e7a-f27339c]
	at net.minecraft.server.v1_8_R3.MinecraftServer.B(MinecraftServer.java:726) [spigot-1.8.7.jar:git-Spigot-f928e7a-f27339c]
	at net.minecraft.server.v1_8_R3.DedicatedServer.B(DedicatedServer.java:367) [spigot-1.8.7.jar:git-Spigot-f928e7a-f27339c]
	at net.minecraft.server.v1_8_R3.MinecraftServer.A(MinecraftServer.java:657) [spigot-1.8.7.jar:git-Spigot-f928e7a-f27339c]
	at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:560) [spigot-1.8.7.jar:git-Spigot-f928e7a-f27339c]
	at java.lang.Thread.run(Thread.java:722) [?:1.7.0_21]