[19:49:30 ERROR]: Could not pass event InventoryClickEvent to JetsPrisonMines v2.3.1
org.bukkit.event.EventException: null
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:309) ~[opprison.jar:git-Spigot-b0f4c22-51c118b]
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:62) ~[opprison.jar:git-Spigot-b0f4c22-51c118b]
        at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:500) ~[opprison.jar:git-Spigot-b0f4c22-51c118b]
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:485) ~[opprison.jar:git-Spigot-b0f4c22-51c118b]
        at net.minecraft.server.v1_13_R2.PlayerConnection.a(PlayerConnection.java:2123) ~[opprison.jar:git-Spigot-b0f4c22-51c118b]
        at net.minecraft.server.v1_13_R2.PacketPlayInWindowClick.a(SourceFile:33) ~[opprison.jar:git-Spigot-b0f4c22-51c118b]
        at net.minecraft.server.v1_13_R2.PacketPlayInWindowClick.a(SourceFile:10) ~[opprison.jar:git-Spigot-b0f4c22-51c118b]
        at net.minecraft.server.v1_13_R2.PlayerConnectionUtils.lambda$0(PlayerConnectionUtils.java:9) ~[opprison.jar:git-Spigot-b0f4c22-51c118b]
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [?:1.8.0_191]
        at java.util.concurrent.FutureTask.run(FutureTask.java:266) [?:1.8.0_191]
        at net.minecraft.server.v1_13_R2.SystemUtils.a(SourceFile:199) [opprison.jar:git-Spigot-b0f4c22-51c118b]
        at net.minecraft.server.v1_13_R2.MinecraftServer.b(MinecraftServer.java:896) [opprison.jar:git-Spigot-b0f4c22-51c118b]
        at net.minecraft.server.v1_13_R2.DedicatedServer.b(DedicatedServer.java:417) [opprison.jar:git-Spigot-b0f4c22-51c118b]
        at net.minecraft.server.v1_13_R2.MinecraftServer.a(MinecraftServer.java:831) [opprison.jar:git-Spigot-b0f4c22-51c118b]
        at net.minecraft.server.v1_13_R2.MinecraftServer.run(MinecraftServer.java:729) [opprison.jar:git-Spigot-b0f4c22-51c118b]
        at java.lang.Thread.run(Thread.java:748) [?:1.8.0_191]
Caused by: java.lang.NullPointerException
        at me.jet315.prisonmines.gui.GUIItem.toItemStack(GUIItem.java:123) ~[?:?]
        at me.jet315.prisonmines.gui.pages.MineBlocks.createInventory(MineBlocks.java:58) ~[?:?]
        at me.jet315.prisonmines.gui.pages.MineBlocks.<init>(MineBlocks.java:25) ~[?:?]
        at me.jet315.prisonmines.gui.pages.MinePanel.executeClick(MinePanel.java:137) ~[?:?]
        at me.jet315.prisonmines.listeners.InventoryListeners.onPlayerInventoryClick(InventoryListeners.java:21) ~[?:?]
        at sun.reflect.GeneratedMethodAccessor73.invoke(Unknown Source) ~[?:?]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_191]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_191]
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:305) ~[opprison.jar:git-Spigot-b0f4c22-51c118b]
        ... 15 more