Jon Krakauer, 30 years after surviving Everest’s deadliest day, still worries about the climbing season. Everest’s season is off to a “terrible start” due to a Khumbu Icefall closure, delaying acclimatization. Krakauer’s bestselling memoir, “Into Thin Air,” about the 1996 tragedy, has a new edition. It’s been 30 years since Jon Krakauer survived one of the worst disasters on Mount Everest. But every spring, when climbing season on the world’s tallest peak hits, he still worries. “I get this knot in my stomach. It sort of hit its peak around May 10,” he told The Post in an exclusive interview. “This year it’s worse than ever . . . Everest season has gotten off to a terrible start.” He’s been following the conditions, as he does every year. He’s worried about a massive ice column that closed the Khumbu Icefall — a notoriously treacherous route towards the beginning of the journey up Everest that climbers typically traverse several times as they acclimatize — for weeks.…