I'll also add, GitHub is not OpenID Connect compliant and may or may not work great.
It only "works" because of the documented configuration which allows us to work around their deficiency.
There is an open feature for Login with GitHub.
https://github.com/FusionAuth/fusionauth-issues/issues/33
The most ideal scenario is for GitHub to offer an OpenID Connect compliant login option so that standards based libraries and products like FusionAuth can properly support them without building one off implementations to adjust to their flavor.