Revoking access to the Sourcegraph OAuth app doesn't trigger an error with code host connection

Created by: quinnkeast

Steps to reproduce:

1. Create a code host connection with Cloud <> GitHub.
2. Go into your personal settings in GitHub and revoke access for the Sourcegaph OAuth app.
3. Return to Sourcegraph > Settings > Code host connections.

Expected behavior:

An error is shown related to the revoked code host.

Actual behavior:

It appears that nothing's wrong with the connection.