Beanie Feldstein, as 16-year-old burgeoning music critic Johanna Morrigan, sobs quietly in a bathroom. She’s just been laughed out of the office by the snobbish lads of an indie rock magazine, having submitted an agonizingly earnest review of the “Annie” soundtrack for print in their alt-weekly. She’s perched under the sinks when she hears a voice: It’s Björk, coming alive inside a framed poster on the bathroom wall.