How Charli XCX, Caroline Polachek and Christine and Queens

As he prepares to release the brightest album of his career as a solo pop artist, “Crash”, Charlie XCX was in stagnation. In December, the British singer-songwriter had a high-stakes “Saturday Night Live” performance featuring two of her friends and collaborators. Caroline Polachek and Christine and the Queens. After a maze of planning, rehearsals, and …