The vibe coded part of my product wasn't the code, it was the error messages

I let the model write every empty state and failure string in my app because it was fast and the copy read fine.

Then a generation path started failing and the message it showed was calm, vague and reassuring. Nobody reported it. I found it in the logs, not in support, and by then it had been broken for over a week. The writing was good enough to hide a real bug.

So the rule I'd give anyone shipping fast: let the model write your happy path copy, write your failure copy yourself. Error text is the one place in a product where sounding confident and pleasant actively works against you. You want it specific and a bit alarming, because you need the user to tell you.

Has anyone else had the generated part be too polished to notice it was wrong?