[21:21:25 ERROR]: Could not pass event InventoryClickEvent to megakilof v1.0
org.bukkit.event.EventException: null
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:306) ~[server.jar:git-Spigot-da42974-8f47214]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[server.jar:git-Spigot-da42974-8f47214]
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:499) [server.jar:git-Spigot-da42974-8f47214]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:484) [server.jar:git-Spigot-da42974-8f47214]
at net.minecraft.server.v1_12_R1.PlayerConnection.a(PlayerConnection.java:1878) [server.jar:git-Spigot-da42974-8f47214]
at net.minecraft.server.v1_12_R1.PacketPlayInWindowClick.a(SourceFile:33) [server.jar:git-Spigot-da42974-8f47214]
at net.minecraft.server.v1_12_R1.PacketPlayInWindowClick.a(SourceFile:10) [server.jar:git-Spigot-da42974-8f47214]
at net.minecraft.server.v1_12_R1.PlayerConnectionUtils$1.run(SourceFile:13) [server.jar:git-Spigot-da42974-8f47214]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_151]
at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_151]
at net.minecraft.server.v1_12_R1.SystemUtils.a(SourceFile:46) [server.jar:git-Spigot-da42974-8f47214]
at net.minecraft.server.v1_12_R1.MinecraftServer.D(MinecraftServer.java:748) [server.jar:git-Spigot-da42974-8f47214]
at net.minecraft.server.v1_12_R1.DedicatedServer.D(DedicatedServer.java:406) [server.jar:git-Spigot-da42974-8f47214]
at net.minecraft.server.v1_12_R1.MinecraftServer.C(MinecraftServer.java:679) [server.jar:git-Spigot-da42974-8f47214]
at net.minecraft.server.v1_12_R1.MinecraftServer.run(MinecraftServer.java:577) [server.jar:git-Spigot-da42974-8f47214]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_151]
Caused by: java.lang.NullPointerException
at pl.daffit.megakilof.listener.InventoryClickListener.onInventoryClickEvent(InventoryClickListener.java:21) ~[?:?]
at sun.reflect.GeneratedMethodAccessor360.invoke(Unknown Source) ~[?:?]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_151]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_151]
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:302) ~[server.jar:git-Spigot-da42974-8f47214]
... 15 more