Sure you should have tests, sure you shouldn't copy paste code you don't understand and you shouldn't push directly to production.
But, regardless of all that, the main issue of all this incident is not the rookie mistake itself, is how they didn't have logs or alerts and it took them 5 days of customer complaining to find out they had "duplication errors" in the db.
That's the thing that should have been fixed first and extensivly mentioned in the post-mortem
The idea of moving fast is to have extensive logs and alerts so you fix all error fasts while they appear without "wasting time" with long expensive tests in a phase where things change every day.
5 days to find out you have "duplicate key" errors in the db is the opposite of fast
CEO thoughts: "Oh post-morten are always well received, I should write one for that very really basic bug we had and how we took 5 days to find it, and forget to mention how we fix it or how we have changed our structure so that it never happen again"
Also the CEO: "remember to be defensive on reddit comments saying how we are a small 1 million dollar backed startup and how it's normal do to this king of rookies mistake to be fast."
Sure not having tests, is bad. Doing thing with AI without triple checking is dangerous.
But not having error logging/alerts on your db ? That's the crazy part.
This is a new product, is not legacy code from 20 years ago when they thought it was a neat idea to just throw stuff at the db raw, and check for db errors to do data validation, so alerts are hard because there's so many expected errrors.
ChatGPT-4o might spot it when asking about the code directly, but this was a conversion from js to python, errors where chatgpt/copilot or any other AI will allucinate or make mistakes to be as close as the original code are very common in my experience.
The other common issue is if the original code has thinsg chatgpt doesn't like (misspell, slightly wrong formatting) it will fix it automatically, or if he really think you should have added a particular field you didn't add.
Sure you should have tests, sure you shouldn't copy paste code you don't understand and you shouldn't push directly to production.
But, regardless of all that, the main issue of all this incident is not the rookie mistake itself, is how they didn't have logs or alerts and it took them 5 days of customer complaining to find out they had "duplication errors" in the db.
That's the thing that should have been fixed first and extensivly mentioned in the post-mortem