[19:33:51] [Server thread/ERROR]: Could not pass event InventoryClickEvent to MysteryBox v1.0-SNAPSHOT
org.bukkit.event.EventException: null
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:320) ~[spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:520) ~[spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:505) ~[spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.PlayerConnection.a(PlayerConnection.java:2158) ~[spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.PacketPlayInWindowClick.a(SourceFile:33) ~[spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.PacketPlayInWindowClick.a(SourceFile:10) ~[spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.PlayerConnectionUtils.lambda$0(PlayerConnectionUtils.java:13) ~[spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.TickTask.run(SourceFile:18) [spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.IAsyncTaskHandler.executeTask(SourceFile:135) [spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) [spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.IAsyncTaskHandler.executeNext(SourceFile:114) [spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.MinecraftServer.aW(MinecraftServer.java:895) [spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.MinecraftServer.executeNext(MinecraftServer.java:888) [spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.IAsyncTaskHandler.executeAll(SourceFile:99) [spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.MinecraftServer.sleepForTick(MinecraftServer.java:871) [spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at net.minecraft.server.v1_14_R1.MinecraftServer.run(MinecraftServer.java:805) [spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        at java.lang.Thread.run(Unknown Source) [?:1.8.0_221]
Caused by: java.lang.NullPointerException
        at com.chefren.mysterybox.clickevent.onclick(clickevent.java:23) ~[?:?]
        at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_221]
        at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_221]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:316) ~[spigot.jar:git-Spigot-03bd4b0-fcb9f90]
        ... 17 more