Knowing that what we imagine is more terrifying than what we see, “The Midnight Sky” plays the end of the world pretty close to the vest, with nary a devastated cityscape to be seen. It is a canny move for a movie that pivots around an apocalyptic disaster, and one that pays off at times by refocusing the story from the spectacle of loss to its rending emotional reality. But while less-is-more tends to be a smart play when trying for awards season credibility, there are times when George Clooney’s latest directorial effort trips up on its own earnestness.