This seems very odd.
The logs that you are receiving in production.log are the only logs GreenLight has. There have been some minor issues popping up with the LDAP authentication, but Google authentication should work fine.
When did you install GreenLight?
Are you using docker? If so did you pull bigbluebutton/greenlight or bigbluebutton/greenlight:master?
Did you build from the repo?
Are you sure your Google credentials are valid and setup correctly? Did you set the authorized redirect URI in the Google console?