Charlie Amter In Sun Tzu’s “The Art of War,” the author advises that “in the midst of chaos, there is also opportunity.” Organizers of Serbia’s Exit Festival took that message to heart over the weekend, as they pulled off a largely successful (and, they hope, safe) music festival, the biggest in Europe since the pandemic began.Held every July in and around Novi Sad’s sprawling Petrovaradin Fortress, Exit Festival drew around 180,000 people spread across four nights (the event wrapped up in the