How to update a person module in Divi

Most people assume that once a website is built and handed over, it's been checked. That buttons go somewhere. That the links work. That there aren't any leftover placeholder pages sitting quietly in the background, completely live, completely visible to Google,...

You update a plugin. The screen goes white. Your website has vanished. Or maybe you haven't touched anything at all — and it's still broken. A page that used to work just… doesn't. The checkout isn't taking payments. Something looks wrong but you can't put your finger...