Verbose error output for authenticated requests

Created by: valerybugakov

Steps to reproduce:

1. Go to the dogfood instance as an unauthenticated user.
2. See verbose errors in the console.

Expected behavior:

1. 401 errors are expected
2. We should not have unexpected token P in JSON at position 0 error messages in the console.

/cc @taylorsperry @jasongornall