[16:28:27] [Server thread/ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'ah' in plugin AuctionHouse v3.2
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:151) ~[patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.craftbukkit.v1_11_R1.CraftServer.dispatchCommand(CraftServer.java:674) ~[patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.PlayerConnection.handleCommand(PlayerConnection.java:1383) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.PlayerConnection.chat(PlayerConnection.java:1292) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.craftbukkit.v1_11_R1.entity.CraftPlayer.chat(CraftPlayer.java:316) [patched_1.11.2.jar:git-Paper-993]
	at it.mri.mycommand.execute.DispatchCommands.ExecuteCommands(DispatchCommands.java:1102) [MyCommand.jar:?]
	at it.mri.mycommand.execute.DispatchCommands.PerformMycmdCommands(DispatchCommands.java:986) [MyCommand.jar:?]
	at it.mri.mycommand.execute.DispatchCommands.ExecuteMyCommandCommands(DispatchCommands.java:335) [MyCommand.jar:?]
	at it.mri.mycommand.listener.PreprocessEvent.onPlayerCommandPreprocess(PreprocessEvent.java:240) [MyCommand.jar:?]
	at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor279.execute(Unknown Source) [?:?]
	at org.bukkit.plugin.EventExecutor$1.execute(EventExecutor.java:44) [patched_1.11.2.jar:git-Paper-993]
	at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:78) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:517) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:502) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.PlayerConnection.handleCommand(PlayerConnection.java:1375) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.PlayerConnection.chat(PlayerConnection.java:1292) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.craftbukkit.v1_11_R1.entity.CraftPlayer.chat(CraftPlayer.java:316) [patched_1.11.2.jar:git-Paper-993]
	at me.messageofdeath.CommandNPC.Listener.NPCListener.onClick(NPCListener.java:52) [CommandNPC.jar:?]
	at me.messageofdeath.CommandNPC.Listener.NPCListener.onRight(NPCListener.java:30) [CommandNPC.jar:?]
	at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor847.execute(Unknown Source) [?:?]
	at org.bukkit.plugin.EventExecutor$1.execute(EventExecutor.java:44) [patched_1.11.2.jar:git-Paper-993]
	at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:78) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:517) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:502) [patched_1.11.2.jar:git-Paper-993]
	at net.citizensnpcs.EventListen.onPlayerInteractEntity(EventListen.java:414) [Citizens.jar:?]
	at com.destroystokyo.paper.event.executor.asm.generated.GeneratedEventExecutor504.execute(Unknown Source) [?:?]
	at org.bukkit.plugin.EventExecutor$1.execute(EventExecutor.java:44) [patched_1.11.2.jar:git-Paper-993]
	at co.aikar.timings.TimedEventExecutor.execute(TimedEventExecutor.java:78) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:517) [patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:502) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.PlayerConnection.a(PlayerConnection.java:1566) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.PacketPlayInUseEntity.a(PacketPlayInUseEntity.java:49) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.PacketPlayInUseEntity.a(PacketPlayInUseEntity.java:6) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.PlayerConnectionUtils$1.run(SourceFile:13) [patched_1.11.2.jar:git-Paper-993]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_111]
	at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_111]
	at net.minecraft.server.v1_11_R1.SystemUtils.a(SourceFile:46) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.MinecraftServer.D(MinecraftServer.java:817) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.DedicatedServer.D(DedicatedServer.java:403) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.MinecraftServer.C(MinecraftServer.java:749) [patched_1.11.2.jar:git-Paper-993]
	at net.minecraft.server.v1_11_R1.MinecraftServer.run(MinecraftServer.java:648) [patched_1.11.2.jar:git-Paper-993]
	at java.lang.Thread.run(Thread.java:745) [?:1.8.0_111]
Caused by: java.lang.IllegalArgumentException: Cannot copy null stack
	at org.apache.commons.lang.Validate.notNull(Validate.java:192) ~[patched_1.11.2.jar:git-Paper-993]
	at org.bukkit.inventory.ItemStack.<init>(ItemStack.java:135) ~[patched_1.11.2.jar:git-Paper-993]
	at net.cfilatov.auctionhouse.menu.MenuRenderer.renderAuctionPage(MenuRenderer.java:115) ~[?:?]
	at net.cfilatov.auctionhouse.menu.MenuRenderer.openAuction(MenuRenderer.java:35) ~[?:?]
	at net.cfilatov.auctionhouse.commands.CommandHandler.handleAuction(CommandHandler.java:75) ~[?:?]
	at net.cfilatov.auctionhouse.commands.CommandHandler.onCommand(CommandHandler.java:51) ~[?:?]
	at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[patched_1.11.2.jar:git-Paper-993]
	... 45 more