OAUTH - GOOGLE - CREDENTIALS ISSUE

I'm trying to add events using the Google API - OAUTH2.

There are 2 ways to do this:

👍 From the client side when the client gives permission to the APP, and also receives a code, then the event is created and everyone is happy.
👎 The error arises when I try to create it from a background job: that is, I do NOT have the code available. However, according to Google's documentation, it should be as easy as:

oauth2Client.setCredentials({
refresh_token: STORED_REFRESH_TOKEN
});
https://developers.google.com/identity/protocols/oauth2/web-server#creatingclient

I've already tried thousands of ways but in the end, I only committed the way that supposedly works for others to review and give me feedback. Thank you.

You can find the code in:
https://github.com/easyRS/easyRS/blob/ft-basic-auth/lib/drivers/network/googleapis.tsx#L73

The error message is also completely generic: