error!

Could not pass event InventoryClickEvent to chunkgui v1.0
org.bukkit.event.EventException: null
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:500) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:485) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at net.minecraft.server.v1_12_R1.PlayerConnection.a(PlayerConnection.java:1891) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at net.minecraft.server.v1_12_R1.PacketPlayInWindowClick.a(SourceFile:33) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at net.minecraft.server.v1_12_R1.PacketPlayInWindowClick.a(SourceFile:10) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at net.minecraft.server.v1_12_R1.PlayerConnectionUtils$1.run(SourceFile:13) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) [?:1.8.0_211]
        at java.util.concurrent.FutureTask.run(Unknown Source) [?:1.8.0_211]
        at net.minecraft.server.v1_12_R1.SystemUtils.a(SourceFile:46) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:748) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:406) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:679) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:577) [spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_211]
Caused by: java.lang.NullPointerException
        at me.tylercreator.guichunk.utilities.Utilities.createItem(Utilities.java:27) ~[?:?]
        at me.tylercreator.guichunk.ui.gui.clicked(gui.java:68) ~[?:?]
        at me.tylercreator.guichunk.listener.ClickListener.onClick(ClickListener.java:30) ~[?:?]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_211]
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_211]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_211]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_211]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[spigot-1.12.2.jar:git-Spigot-dcd1643-e60fc34]