auction

[08:35:19 WARN]: [ApeironAuctionHouse] Plugin ApeironAuctionHouse v1.3 generated an exception while executing task 41636
java.util.ConcurrentModificationException: null
        at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909) ~[?:1.8.0_202]
        at java.util.ArrayList$Itr.next(ArrayList.java:859) ~[?:1.8.0_202]
        at gyurix.auction.gui.MainGUI.lambda$4(MainGUI.java:230) ~[?:?]
        at gyurix.auction.gui.MainGUI$$Lambda$3355.000000003062E200.run(Unknown Source) ~[?:?]
        at org.bukkit.craftbukkit.v1_13_R2.scheduler.CraftTask.run(CraftTask.java:82) ~[patched_1.13.2.jar:git-Paper-"988887d2"]
        at org.bukkit.craftbukkit.v1_13_R2.scheduler.CraftAsyncTask.run(CraftAsyncTask.java:52) ~[patched_1.13.2.jar:git-Paper-"988887d2"]
        at com.destroystokyo.paper.ServerSchedulerReportingWrapper.run(ServerSchedulerReportingWrapper.java:22) ~[patched_1.13.2.jar:git-Paper-"988887d2"]
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:1.8.0_202]
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:1.8.0_202]
        at java.lang.Thread.run(Thread.java:813) [?:1.8.0_202]