[HHad3]

Not storing raw HTML might be a last resort to avoid these kinds of bugs in other software, but a good amount of things need to go wrong for them to happen in the first place. The issue is that your data is rendered outside of your software and known-good environment, so all bets are off.

You could as well have triggered a bug in some LaTeX engine that happened to be configured to allow arbitrary shell command execution.

Another strategy to defend against these issue you describe would be to not let developers access raw production data in the first place, but always anonymize it first, or remove internet access from machines accessing production data. (How sensitive is the data in your users table? Could a developer's test script accidentally send emails to your live users?)