With a signature on a dotted line, fitness center users are barred from successfully suing for a wide array of possible injuries or accidents associated with going to the gym. On Wednesday, a state appeals panel ruled that a falling mirror isn’t one of those kinds of injuries. In a 14-page opinion, 1st District Appellate Justice Michael B. Hyman wrote that an exculpatory clause in a Chicago gym’s membership agreement only covers dangers one might ordinarily expect to occur at a gym. In September 2010 …