UCError4

Exception in thread "Craft Scheduler Thread - 626"
org.apache.commons.lang.UnhandledException: Plugin UltraCosmetics v2.1.2 generated an exception while executing task 830
	at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:57)
	at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at be.isach.ultracosmetics.run.FallDamageManager.run(FallDamageManager.java:32)
	at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftTask.run(CraftTask.java:58)
	at org.bukkit.craftbukkit.v1_9_R1.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:53)
	... 4 more