20:18:18 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'ma' in plugin MobArena v0.92
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:37)
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:129)
        at org.bukkit.craftbukkit.CraftServer.dispatchCommand(CraftServer.java:298)
        at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:711)
        at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:676)
        at org.bukkit.craftbukkit.entity.CraftPlayer.chat(CraftPlayer.java:144)
        at com.laytonsmith.aliasengine.AliasCore$1.done(AliasCore.java:92)
        at com.laytonsmith.aliasengine.Script.run(Script.java:99)
        at com.laytonsmith.aliasengine.AliasCore.alias(AliasCore.java:83)
        at com.sk89q.commandhelper.CommandHelperListener.runAlias(CommandHelperListener.java:88)
        at com.sk89q.commandhelper.CommandHelperListener.onPlayerCommandPreprocess(CommandHelperListener.java:132)
        at org.bukkit.plugin.java.JavaPluginLoader$5.execute(JavaPluginLoader.java:272)
        at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:58)
        at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:321)
        at net.minecraft.server.NetServerHandler.handleCommand(NetServerHandler.java:704)
        at net.minecraft.server.NetServerHandler.chat(NetServerHandler.java:676)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:669)
        at net.minecraft.server.Packet3Chat.a(Packet3Chat.java:33)
        at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:84)
        at net.minecraft.server.NetworkListenThread.a(SourceFile:105)
        at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:451)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:361)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:422)
Caused by: java.lang.NullPointerException
        at com.garbagemule.MobArena.MAUtils.sitPets(MAUtils.java:569)
        at com.garbagemule.MobArena.Arena.playerJoin(Arena.java:256)
        at com.garbagemule.MobArena.MACommands.onCommand(MACommands.java:193)
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:35)
        ... 23 more