- When the user is not found in `reloadparam`, early return when the
user is not found to avoid calling `IsUserVisibleToViewer` which in turn
avoids causing a NPE.
- This fixes the case that a 500 error and 404 error is shown on the
same page.
- Add integration test for non-existant user RSS.
- Regression by c6366089df
(cherry picked from commit f0e06962786ef8c417b0c6f07940c1909d3b91ba)
(cherry picked from commit 75d806690875a4fc38eb1e3c904096be34657011)
(cherry picked from commit 4d0a1e0637450865c7bbac69e42d92d63b95149c)
(cherry picked from commit 5f40a485da1b2c5f129f32e2ddc2065e3ba9ccd0)