Forking from discussions on T254950: Performance review of WikimediaApiPortalOAuth extension, it seems beneficial if the extension had better/more specific error handling for a number of cases, rather than just giving "Request failed. Please try again later" seemingly for both CORS issues (which isn't anything that just "trying again later" will fix, unless the code is fixed, and potentially also for email not confirmed (which is being tracked in T267429: Errors when creating clients and looks like some sort of false positive, but that's a different issue)