In “Robin’s Wish,” a documentary about the last days of Robin Williams, the comedian’s widow, Susan Schneider Williams, recalls one of the first times that she could tell something was seriously off. Robin called her from Vancouver, where he was shooting the third “Night at the Museum” film, and he couldn’t calm himself down. He was having a panic attack over the fact that he couldn’t remember his lines; at times, he was having trouble remembering even one line of dialogue. That wasn’t a problem he’d ever had before, and given that he was one of the most mentally nimble people ever created, you can see how disturbing this might have been. Shawn Levy, the “Night at the Museum” director, recalls Robin telling him, “I don’t know what’s going on. I’m not me anymore.” His mind, says Levy, “was not firing at the same speed. That spark was diminished.”