GitLab: No redirect_uri in the db for web-internal clientKey leads to one-click DoS on gitter.im

Summary In the oauthclients collection of the default gitter installation, there's no value registeredRedirectUri in the database for web-internal clientKey. The request to /login/oauth/authorize?responsetype=code&clientid=web-internal&redirecturi=http://whatever causes the app to crash when tryi...