That’s law. My mother told me you never show up anywhere empty-handed. If you’re not sure what to bring, ask the host what they need.
If they’re nice and say they don’t need anything, bring the host’s fave wine/drink/dessert.
But don’t show up with NOTHING. That’s tacky
Whenever any one of my friends or family members is having something, I always offer to bring something. It may not be big but I’ll get the sodas/waters etc . They don’t have to ask me