It’s difficult to even pick a starting point on the many misfires that are musician-turned-filmmaker Sia’s misguided directorial debut, “Music.” So much of it is bad and ill-conceived, all of it worth criticizing in various ways. There’s the infantilizing use of an autistic character, who the film portrays as nonverbal but never has the bravery to explicitly identify as autistic, who ends up being the magic push an adult screwup needs to get her life in order. You know, the same narrative device Adam Sandler’s “Big Daddy” used only with more nuance than this? Yes. But while the flaws of “Music” begin with casting neurotypical and able-bodied dance prodigy Maddie Ziegler to play a character with autism spectrum disorder, they extend past her: into the exhaustingly predictable plot, the underdeveloped nature of Kate Hudson’s and Leslie Odom Jr.’s characters, and the thoroughly twee dance sequences. This movie is literally and figuratively saying music can save your life, but the execution is all treacle and dust—overly sweet and utterly empty.