Stop using `http.StatusPreconditionFailed` as a response status code

There is no reason we should be using this status code anywhere. 

According to the docs it is for very specific HTTP header reasons.

 https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/412#:~:text=The%20HyperText%20Transfer%20Protocol%20(HTTP,target%20resource%20has%20been%20denied.
