Some file loading is still not npe save, if the world having been saved is not there anymore afterwards it will throw npe during loading those worlds

http://forums.bukkit.org/threads/tp-chat-deathtpplus-v-3-9-16-2262-deathnotify-deathtp-tombstones-tomb-and-more-cb-1-3-2.40055/page-12#post-1364576