[01:58:23 ERROR]: Could not pass event ItemSpawnEvent to UltimateStacker v1.11.2
java.lang.IllegalArgumentException: Cannot drop air
at com.google.common.base.Preconditions.checkArgument(Preconditions.java:122) ~[patched_1.13.2.jar:git-Paper-641]
at net.minecraft.server.v1_13_R2.EntityItem.setItemStack(EntityItem.java:410) ~[patched_1.13.2.jar:git-Paper-641]
at org.bukkit.craftbukkit.v1_13_R2.entity.CraftItem.setItemStack(CraftItem.java:34) ~[patched_1.13.2.jar:git-Paper-641]
at com.songoda.ultimatestacker.UltimateStacker.updateItemAmount(UltimateStacker.java:397) ~[?:?]
at com.songoda.ultimatestacker.listeners.ItemListeners.onExist(ItemListeners.java:78) ~[?:?]
at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor864.execute(Unknown Source) ~[?:?]
at org.bukkit.plugin.EventExecutor.lambda$create$1(EventExecutor.java:69) ~[patched_1.13.2.jar:git-Paper-641]
at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:80) ~[patched_1.13.2.jar:git-Paper-641]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:66) ~[patched_1.13.2.jar:git-Paper-641]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:520) ~[patched_1.13.2.jar:git-Paper-641]
at org.bukkit.craftbukkit.v1_13_R2.event.CraftEventFactory.callItemSpawnEvent(CraftEventFactory.java:507) ~[patched_1.13.2.jar:git-Paper-641]
at org.bukkit.craftbukkit.v1_13_R2.event.CraftEventFactory.doEntityAddEventCalling(CraftEventFactory.java:401) ~[patched_1.13.2.jar:git-Paper-641]
at net.minecraft.server.v1_13_R2.World.addEntity(World.java:1095) ~[patched_1.13.2.jar:git-Paper-641]
at net.minecraft.server.v1_13_R2.WorldServer.addEntity(WorldServer.java:942) ~[patched_1.13.2.jar:git-Paper-641]
at org.bukkit.craftbukkit.v1_13_R2.CraftWorld.dropItem(CraftWorld.java:372) ~[patched_1.13.2.jar:git-Paper-641]
at com.songoda.epicfarming.utils.Methods.animate(Methods.java:82) ~[?:?]
at com.songoda.epicfarming.tasks.EntityTask.run(EntityTask.java:77) ~[?:?]
at org.bukkit.craftbukkit.v1_13_R2.scheduler.CraftTask.run(CraftTask.java:84) ~[patched_1.13.2.jar:git-Paper-641]
at org.bukkit.craftbukkit.v1_13_R2.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:449) ~[patched_1.13.2.jar:git-Paper-641]
at net.minecraft.server.v1_13_R2.MinecraftServer.b(MinecraftServer.java:1010) ~[patched_1.13.2.jar:git-Paper-641]
at net.minecraft.server.v1_13_R2.DedicatedServer.b(DedicatedServer.java:439) ~[patched_1.13.2.jar:git-Paper-641]
at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:940) ~[patched_1.13.2.jar:git-Paper-641]
at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:837) ~[patched_1.13.2.jar:git-Paper-641]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_212]