[20:29:22 WARN]: [UpgradeableHoppers] Failed to progress item transfer for hopper: Hopper{coordinate=Coordinate{world=skyblock,x=2423,y=0,z=3167},id=1011}
[20:29:22 WARN]: java.util.ConcurrentModificationException
[20:29:22 WARN]:        at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:909)
[20:29:22 WARN]:        at java.util.ArrayList$Itr.next(ArrayList.java:859)
[20:29:22 WARN]:        at net.minecraft.server.v1_14_R1.World.getType(World.java:719)
[20:29:22 WARN]:        at net.minecraft.server.v1_14_R1.TileEntity.update(TileEntity.java:144)
[20:29:22 WARN]:        at net.minecraft.server.v1_14_R1.TileEntityLootable.setItem(TileEntityLootable.java:104)
[20:29:22 WARN]:        at net.minecraft.server.v1_14_R1.InventoryLargeChest.setItem(InventoryLargeChest.java:106)
[20:29:22 WARN]:        at org.bukkit.craftbukkit.v1_14_R1.inventory.CraftInventory.setItem(CraftInventory.java:99)
[20:29:22 WARN]:        at org.bukkit.craftbukkit.v1_14_R1.inventory.CraftInventory.addItem(CraftInventory.java:320)
[20:29:22 WARN]:        at me.angeschossen.upgradeablehoppers.c.a.a.b.addItem(F:173)
[20:29:22 WARN]:        at me.angeschossen.upgradeablehoppers.j.d.a(F:63)
[20:29:22 WARN]:        at me.angeschossen.upgradeablehoppers.j.d.a(F:27)
[20:29:22 WARN]:        at me.angeschossen.upgradeablehoppers.i.c.c(F:80)
[20:29:22 WARN]:        at java.lang.Iterable.forEach(Iterable.java:75)
[20:29:22 WARN]:        at me.angeschossen.upgradeablehoppers.i.c.run(F:57)
[20:29:22 WARN]:        at java.util.TimerThread.mainLoop(Timer.java:555)
[20:29:22 WARN]:        at java.util.TimerThread.run(Timer.java:505)