Amazon’s cutting-edge delivery drones fell from the sky during a December test flight after a software update made them vulnerable to rain — an avoidable disaster made worse by the company’s decision to remove a critical safety sensor, according to a report citing federal documents.The twin crashes of Amazon’s MK30 drones in Oregon occurred just minutes apart on Dec. 16, when both aircraft abruptly shut off mid-air at an altitude of more than 200 feet and slammed into the ground, Bloomberg News reported.The ...