The Kansas City Chiefs have taken out an insurance policy on the contract of star quarterback Patrick Mahomes — a rare occurrence in the NFL, ESPN’s Field Yates reported Thursday.The Super Bowl champion Chiefs open their season Thursday night against the Houston Texans. In the offseason, they gave Mahomes the richest contract in American sports history, a 10-year extension that could be worth as much as $503 million.The insurance would kick in should an injury keep Mahomes from fulfilling his contract, which runs through 2031. The Chiefs guaranteed $140 million of the money against injury, and the insurance likely would give them the option to recoup some of those funds.ESPN said the insurance also would provide Kansas City with a salary-cap credit of Mahomes’ salary should he be sidelined.Mahomes, who turns 25 next week, is entering his third season as the Chiefs’ starter. His achievements over the first two seasons? A league Most Valuable Player award, an All-Pro and two Pro Bowl selections, and a Super Bowl championship.