17:38:22 [SEVERE] Could not pass event PlayerInteractEvent to GB.Shopper
org.bukkit.event.EventException
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:303)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.jav
a:62)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.j
ava:459)
        at org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerInteractEven
t(CraftEventFactory.java:176)
        at net.minecraft.server.ItemInWorldManager.interact(ItemInWorldManager.j
ava:287)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:636)
        at net.minecraft.server.Packet15Place.handle(SourceFile:39)
        at net.minecraft.server.NetworkManager.b(NetworkManager.java:229)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:113)
        at net.minecraft.server.NetworkListenThread.a(NetworkListenThread.java:7
8)
        at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:551)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:449)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:492)
Caused by: org.bukkit.command.CommandException: Unhandled exception executing co
mmand 'gbshopper' in plugin GB.Shopper v1.8
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:42)
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:16
6)
        at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:4
73)
        at dk.gladblad.flyvehest.gbshopper.SignInteractionListener.onPlayerInter
action(SignInteractionListener.java:94)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.ja
va:301)
        ... 12 more
Caused by: java.lang.NullPointerException
        at dk.gladblad.flyvehest.gbshopper.GBShopperCommandExecutor.onCommand(GB
ShopperCommandExecutor.java:176)
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:40)
        ... 20 more