20:16:27 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'walls' in plugin TheWalls v1.1.0.1
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46)
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:189)
        at org.bukkit.craftbukkit.v1_5_R3.CraftServer.dispatchCommand(CraftServer.java:546)
        at net.minecraft.server.v1_5_R3.PlayerConnection.handleCommand(PlayerConnection.java:979)
        at net.minecraft.server.v1_5_R3.PlayerConnection.chat(PlayerConnection.java:895)
        at net.minecraft.server.v1_5_R3.PlayerConnection.a(PlayerConnection.java:840)
        at net.minecraft.server.v1_5_R3.Packet3Chat.handle(Packet3Chat.java:44)
        at org.spigotmc.netty.NettyNetworkManager.b(NettyNetworkManager.java:187)
        at net.minecraft.server.v1_5_R3.PlayerConnection.d(PlayerConnection.java:109)
        at net.minecraft.server.v1_5_R3.ServerConnection.b(SourceFile:35)
        at org.spigotmc.MultiplexingServerConnection.b(MultiplexingServerConnection.java:72)
        at net.minecraft.server.v1_5_R3.MinecraftServer.r(MinecraftServer.java:583)
        at net.minecraft.server.v1_5_R3.DedicatedServer.r(DedicatedServer.java:227)
        at net.minecraft.server.v1_5_R3.MinecraftServer.q(MinecraftServer.java:472)
        at net.minecraft.server.v1_5_R3.MinecraftServer.run(MinecraftServer.java:404)
        at net.minecraft.server.v1_5_R3.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.NullPointerException
        at rubik_cube_man.plugins.walls.WallsCommand.onCommand(WallsCommand.java:224)
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
        ... 15 more