buildTo(Locatable a).step() will throw an NPE sometimes

When I run this code it sometimes throws an NPE and I can't figure out why

Code (Text):

1.  GameObject obelisk = GameObjects.newQuery().names("Small obelisk").results().first();
2.         if (obelisk != null && !obelisk.isVisible()) {
3.             Traversal.getDefaultWeb().getPathBuilder().buildTo(obelisk.getPosition()).step();
4.             Camera.passivelyTurnTo(obelisk);
5.         }

 

Ah thanks! I didn't know that