Code:
java.lang.NullPointerException
        at org.dementhium.content.chardesign.CharacterDesign.interfaceOption(CharacterDesign.java:92)
        at org.dementhium.event.EventManager.handleInterfaceOption(EventManager.java:72)
        at org.dementhium.net.packethandlers.ActionButtonHandler.handleButtons(ActionButtonHandler.java:113)
        at org.dementhium.net.packethandlers.ActionButtonHandler.handlePacket(ActionButtonHandler.java:50)
        at org.dementhium.net.PacketManager.handlePacket(PacketManager.java:54)
        at org.dementhium.net.handler.DementhiumHandler.processPackets(DementhiumHandler.java:28)
        at org.dementhium.task.impl.PlayerTickTask.execute(PlayerTickTask.java:23)
        at org.dementhium.task.SequentialTaskExecutor.performTasks(SequentialTaskExecutor.java:13)
        at org.dementhium.model.World.run(World.java:177)
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
        at java.util.concurrent.FutureTask$Sync.innerRunAndReset(Unknown Source)

        at java.util.concurrent.FutureTask.runAndReset(Unknown Source)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(Unknown Source)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
Everytime a button is being clicked in character design, this nullpointerexception is showing up..

Eventmanager line 72 shows this method.

Code:
 public boolean handleInterfaceOption(Player player, int interfaceId, int buttonId, int slot, int itemId, int opcode) {
        List<EventListener> listeners = interfaceListeners.get(interfaceId);
        boolean handled = false;
        if (listeners != null) {
            for (EventListener listener : listeners) {
                if (listener.interfaceOption(player, interfaceId, buttonId, slot, itemId, opcode)) {
                    handled = true;
                }
            }
        }
        return handled;
    }