PHP

Route [login] not defined.Route [login] not defined.

Use Postman and set the Header `Accept: application/json` otherwise Laravel
Passport would never know it's an API client and thus redirect to a /login 
page for the web.

Route [login] not defined.Route [login] not defined.

You're trying to redirect to a named route whose name is login, but you have
no routes with that name:

Route::post('login', [ 'as' => 'login', 'uses' => 'LoginController@do']);

The 'as' portion of the second parameter defines the name of the route. The 
first string parameter defines its route.