Earlier this morning in a chat with a co-worker, I was asking them whether they could do something, and they dropped the “Only Sith deal in absolutes” quote and without even thinking, I responded with “Do or do not, there is no try,” and it was only just then that Yoda’s latter statement to Luke directly contradicts the earlier statement by Obi-Wan. I started thinking through the implications of that, and then decided it is probably just sloppy writing.