Google Cloud identity token oidcToken.GetAccessTokenAsync() fails and without error message - asp.net-web-api

Question

When calling a google oauth library method, it fails without error - no amount of try/catch-ing traps any error messages.
I am trying to get an identity token much as I would if I executed gcloud auth print-identity-token from the command line using the gcloud cli.
The reason for wanting the identity token is that another Cloud Function service requires it as Authorization : Bearer [token], and indeed works correctly when I stuff a manually generated identity token in my code. That is not a suitable solution for development or production
The code snippet I wrote, cobbled from numerous sources, to procure an identity token is this:
using (var stream = new FileStream(credentialsFilePath, FileMode.Open, FileAccess.Read))
{
var credentials = GoogleCredential.FromStream(stream);
if (credentials.IsCreateScopedRequired)
{
credentials = credentials.CreateScoped(scopes);
}
OidcToken oidcToken = await credentials.GetOidcTokenAsync(
Options
.FromTargetAudience(scopes[0])
.WithTokenFormat(OidcTokenFormat.Standard));
// this line bombs immediately, jumping out of this method and the calling method.
string token = await oidcToken.GetAccessTokenAsync();
return token;
}
In the above code, scopes[0] is left over code from a previous attempt which contains the endpoint to Cloud Function service. https://subdomain.cloudfunctions.net/cloud-function/v1/ is the general form of the cloud function endpoint I am calling as a part of a web api.
Is this a valid and reasonable way to get the equivalent of gcloud auth print-identity-token? If so, why the epic failure?
I need to use a google service account for service to service authentication. Development environment is visual studio 2019, .net core 3.1, docker/linux
PS - the service account has the cloud function's Cloud Functions Invoker role.
PPS - the issue seems to be related to docker and a set of error messages I get when starting my project in docker. I had ignored them as they were not until now impairing functionality.
at System.Net.Http.CurlHandler.ThrowIfCURLEError(CURLcode error)
at System.Net.Http.CurlHandler.MultiAgent.FinishRequest(StrongToWeakReference`1 easyWrapper, CURLcode messageResult)
running the code on windows works.

Answer 1

The penultimate problem is that I needed to make an upstream method asynchronous and add an await. Now the code above works every time. This change led me to the ultimate problem whose solution is some code refactoring in ConfigureServices() related to AddHttpClient() setup.
The curl exception was due to trying to add logger.loggerFactory.AddGoogle(…) with a bad configuration. this has been a bad hair day.
This question is also an example of what not to do - ie I used too much minimalism to describe the problem.