Times health writer Tara Parker-Pope got some unexpected thrills during last night’s performance of Gypsy, which stars Patti Lupone at Broadway’s St. James Theater: Toward the end of the show, as Ms. LuPone’s Mama Rose was about to launch into her show-stopping number, there was a crash in the balcony. A huge metal plate, about 30 inches in diameter and used to cover a diffuser, came crashing down from the ceiling. It hit a young......