NPC 31356 class not found
java.lang.reflect.InvocationTargetException
        at sun.reflect.GeneratedConstructorAccessor21.newInstance(Unknown Source)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
        at net.sf.l2j.gameserver.model.L2Spawn.doSpawn(L2Spawn.java:438)
        at net.sf.l2j.gameserver.model.L2Spawn.init(L2Spawn.java:368)
        at net.sf.l2j.gameserver.datatables.SpawnTable.fillSpawnTable(SpawnTable.java:112)
        at net.sf.l2j.gameserver.datatables.SpawnTable.<init>(SpawnTable.java:59)
        at net.sf.l2j.gameserver.datatables.SpawnTable.<clinit>(SpawnTable.java:44)
        at net.sf.l2j.gameserver.GameServer.<init>(GameServer.java:399)
        at net.sf.l2j.gameserver.GameServer.main(GameServer.java:692)
Caused by: java.lang.NullPointerException
        at net.sf.l2j.gameserver.datatables.NpcWalkerRoutesTable.getRouteForNpc(NpcWalkerRoutesTable.java:117)
        at net.sf.l2j.gameserver.ai.L2NpcWalkerAI.<init>(L2NpcWalkerAI.java:48)
        at net.sf.l2j.gameserver.model.actor.instance.L2NpcWalkerInstance.<init>(L2NpcWalkerInstance.java:48)
        ... 10 more