When a Facebook callback error occurs it renders as [object Object].

How to reproduce

1. Start an example application and navigate to /login.
2. Click the login to Facebook login link.
3. While being on the Facebook OAuth provider page prompting you to authorize your application to access your Facebook account. Go into the Facebook Developer dashboard and remove your whitelisted callback URI.
4. Go back to the Facebook provider page and authorize your application to access the account.
5. You should be redirected back to /login and with an error message stating [object Object] (as shown below):