Check token and organisation access

[frisoft]

If the GH token is expired the error is not clear: "missing response data".

Unfortunately, GH does not return any specific error if the token is expired or invalid. However, I could at least add some other text:
"Missing response data. Check your Github token".

Also, if the token is valid but not authorised by an organisation, GH does not return any result. No error is reported.
I may introduce a step to access some organisation details (org name from --org or --repo) to verify there is a proper authorisation.