* api: return 404 for alloc FS list/stat endpoints
If the alloc filesystem doesn't have a file requested by the List
Files or Stat File API, we currently return a HTTP 500 error with the
expected "file not found" error message. Return a HTTP 404 error
instead.
* update FS Handler
Previously the FS handler would interpret a 500 status as a 404
in the adapter layer by checking if the response body contained
the text or is the response status
was 500 and then throw an error code for 404.
Co-authored-by: Jai Bhagat <jaybhagat841@gmail.com>
