Question: reasonable not handling error on getting procject id from metadata server in google implementation?

I found error on getting procject id is not handled. Is this has any reason?
I actually got empty project id and wanted to know detail reasons.
https://github.com/golang/oauth2/blob/22134a41033e44c2cd074106770ab5b7ca910d15/google/default.go#L217

If OK to handle. I can work on it.