Add test for case where client error is raised as `invalid_credentials`.
Add test for case where client error is raised as `invalid_credentials`.

billy-ran-away/omniauth-oauth2,bino98/omniauth-misoca-oauth2,k-tada/omniauth-oauth2,intridea/omniauth-oauth2,txssseal/omniauth-oauth2,local-ch/omniauth-oauth2,Cloverhound/omniauth-ciscospark