window.opener is null

Having the same problem. I still get the error, that the window.opener is null. It makes sense that it is null, after the redirect to github and back over the callback url. So how is that supposed to work?

_Originally posted by @Tobilo in https://github.com/vencax/netlify-cms-github-oauth-provider/issues/14#issuecomment-1555288883_
            