SaveIt Error

2013-04-22 20:38:38 [INFO] Starting world save...
2013-04-22 20:38:38 [INFO] [SaveIt] [ERROR] Not Existing world in config!
2013-04-22 20:38:38 [WARNING] Unexpected exception while parsing console command "saveit save"
org.bukkit.command.CommandException: Unhandled exception executing command 'saveit' in plugin SaveIt v2.8
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46)
    at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:188)
    at org.bukkit.craftbukkit.v1_5_R2.CraftServer.dispatchCommand(CraftServer.java:523)
    at org.bukkit.craftbukkit.v1_5_R2.CraftServer.dispatchServerCommand(CraftServer.java:512)
    at net.minecraft.server.v1_5_R2.DedicatedServer.am(DedicatedServer.java:261)
    at net.minecraft.server.v1_5_R2.DedicatedServer.r(DedicatedServer.java:226)
    at net.minecraft.server.v1_5_R2.MinecraftServer.q(MinecraftServer.java:474)
    at net.minecraft.server.v1_5_R2.MinecraftServer.run(MinecraftServer.java:407)
    at net.minecraft.server.v1_5_R2.ThreadServerApplication.run(SourceFile:573)
Caused by: java.lang.UnsupportedOperationException
    at java.util.AbstractList.remove(AbstractList.java:161)
    at java.util.AbstractList$Itr.remove(AbstractList.java:374)
    at java.util.AbstractCollection.remove(AbstractCollection.java:283)
    at me.dretax.SaveIt.Main.WorldSaveDelayed(Main.java:243)
    at me.dretax.SaveIt.Main.onCommand(Main.java:159)
    at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44)
    ... 8 more