Nice. I built something basically just like this for work for the same reason last year. It only look a few hours though, cause I just used Acorn [0] to parse my JS, then directly evaluated the AST. It also had an iteration limit and other configurable limits so I can eval stuff in the browser without crashing the tab. I did not use an LLM.

[0]: https://github.com/acornjs/acorn

This is exactly what I wanted and couldn't find. Ended up creating along with an interpreter (so slightly easier then walk and execute)