“IF” may get by. It’s sincere. As the song from “The Music Man” asks: How can there be any sin in that? It’s also maudlin enough to force you into a defensive emotional crouch for an hour and 44 minutes. I speak for an audience of one here. Others may experience an entirely different set of side effects to a movie with a weirdly groggy and medicinal aura. As his popular success with the first two “Quiet Place” monster movies asserted, writer-director John Krasinski knows how to balance thrills and miles and miles and miles of heart.