Bukkit

What steps will reproduce the problem?
1.Type the command /class online
2.
3.

What is the expected output? What do you see instead?
Instead of the list of online players in each classes, I see : "An internal error occurred while attempting to perform this command"

What version of the product are you using?
The last version : 1.0

Do you have an error log of what happened?
Yes, I have :
2013-06-23 13:46:23 [INFO] hantoine issued server command: /class online
2013-06-23 13:46:23 [SEVERE] null
org.bukkit.command.CommandException: Unhandled exception executing command 'class' in plugin Player Classes v1.0
    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:523)
    at net.minecraft.server.v1_5_R3.PlayerConnection.handleCommand(PlayerConnection.java:965)
    at net.minecraft.server.v1_5_R3.PlayerConnection.chat(PlayerConnection.java:883)
    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 net.minecraft.server.v1_5_R3.NetworkManager.b(NetworkManager.java:292)
    at net.minecraft.server.v1_5_R3.PlayerConnection.d(PlayerConnection.java:109)
    at net.minecraft.server.v1_5_R3.ServerConnection.b(SourceFile:35)
    at net.minecraft.server.v1_5_R3.DedicatedServerConnection.b(SourceFile:30)
    at net.minecraft.server.v1_5_R3.MinecraftServer.r(MinecraftServer.java:581)
    at net.minecraft.server.v1_5_R3.DedicatedServer.r(DedicatedServer.java:226)
    at net.minecraft.server.v1_5_R3.MinecraftServer.q(MinecraftServer.java:477)
    at net.minecraft.server.v1_5_R3.MinecraftServer.run(MinecraftServer.java:410)
    at net.minecraft.server.v1_5_R3.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.ArrayIndexOutOfBoundsException: 1
    at uk.co.lukeparker.CommandHandler.onCommand(CommandHandler.java:222)
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
    ... 15 more

Please provide any additional information below.
I run on the 1.5.2-R0.1 craftbukkit version.