Please gracefully handle failures during the refresh token flow

[btrautmann]

I'm running into an issue using this package where there seem to be failures happening in the token refresh flow but all I'm given back at the call site is:

Error: Exception: Provider error 404: null: null

This is actually being hardcoded any time an issue occurs in the refresh codepath via:

AccessTokenResponse.errorResponse() : super.errorResponse();

which points to

OAuth2Response.errorResponse() {
  respMap = {'http_status_code': 404};
}

This makes it very hard to actually reason about what's happening.

To make matters worse, whenever this failure occurs, the library defaults to fetching a new token which results in an auth popup occurring even though the user should still be authenticated. This leads to situations like this:

https://github.com/teranetsrl/oauth2_client/assets/8343465/ccae0b2b-7d41-4b46-884d-551d736860b8

Is there any way a user of this package can work around this experience?

[btrautmann]

Gonna close this; I just wrote my own oauth client that's tailored to my use case.