So, I have a potential problem here. But should I be bothered about the fact that I currently have no ending? My Mind argues with itself thus:

Yes! If you don’t know your ending, what are you going to work towards?
An interesting point. Presumably I’m going to want to foreshadow my ending with hints about how the story will be resolved. I will have to make sure my characters have all the right tools, and that everyone is at the right place at the right time.

No! That’s what other drafts are for! Besides, you want to give yourself enough freedom to make the story end naturally.
I see. Over the course of writing my story, I will likely form a more coherent set of characters. What I’ve planned for them in the end might not fit with the story and people that have evolved as part of the process. Then I’ll be shoehorning an ill-fitting climax to the finish of my story!

Yes! What if you get to the end and you still can’t think if an ending?
Oh, I didn’t think of that. I don’t want to stall at the last hurdle, do I.

No! But how long are you going to wait? And in the meantime, what, you don’t start writing?
Well yes, I have to start some time. Although not writing it at all has a certain appeal. It certainly seems easier…

Yes! No! What!?
You’re right. Forget I said anything.

Or something like that anyway.