Catalytic converter thefts more than tripled in LA County last year, and some victims are replacing the $3,000 car part just to have it stolen again. So Yun Um’s new documentary “Liquor Store Dreams” explores her upbringing in and around her family’s Hawthorne business, plus her complicated relationship with her immigrant parents. The Nickel Diner opened in 2008 in its “Skid Row adjacent” Downtown LA digs. After a pandemic and inflation, it’s shutting down this weekend.