It might be scary to you, but who runs Python at scale? youtube ran it for quite a long time. reddit yelp

Those sites seem mainstays to me, with good load. Perhaps performance is a problem for you for the server load and costs that you want, but it does allow you to iterate quickly to get your product out the door.

Last thing though: Checked errors. I think that's largely solved with type hinting (along the lines of TypeScript) where you get some guarantees.

Stacks of choice though for me is really Python and Go. I would use Go for when I truly need that raw speed with a lot fewer servers in Go in terms of horizontally scaling.