During the Des Moines Metro Opera’s performance of “Carmen” on July 11, an understudy jumped into the bullfighter’s role after an electrical fire flared up in the original star’s trailer and destroyed most of its contents. No one was harmed. The 1962 Airstream Overlander belongs to California bass-baritone Christian Pursell, who uses the trailer as his primary residence while he travels from one engagement to the next, and this summer he is joined by his young son, Winston. Pursell’s colleagues have donated clothing and a few toys and set up a GoFundMe page until his insurance kicks in; they’re also planning a party this week for Winston’s birthday.