That error would get logged in Sentry and should be in stderr.
I don’t know what you’re trying to accomplish as an unattended install, but once you setup SSO anyone on the domain can login and gets an account automatically generated. You can’t automatically configure SSO with robots as it requires proof of ownership to enable.
This is very different than Sentry 8, as Google in Sentry 8 was a convenience function (it was unrelated to SSO). We removed that functionality.