Better error handling?

[nboisnea]

I'm not sure what I am doing wrong with my error handling using apollo-angular. I have a GraphQL API listenning at localhost:8080 and I make a request that is supposed to return a GraphQL error. The server responds with a HTTP 500 error and the response's body looks like this:

{
    "errors": [
        {
            "detailMessage": "Test error",
            "statusCode": 480,
            "message": "Error details",
            "errorCode": 1713213528628
        }
    ],
    "data": {
        "requestThatShouldFail": null
    }
}

In my Angular app I use onError with a callback function but I only get a network error, no GraphQL errors:

function apolloLinkFactory(httpLink: HttpLink) {
  const errorLink = onError(({ graphQLErrors, networkError }) => {
    // Handle errors, but graphQLErrors is always undefined
    // networkError is an HttpErrorReponse
  });

  const link = httpLink.create({
    uri: 'http://localhost:8080'
  });

  return {
    cache: new InMemoryCache(),
    link: errorLink.concat(link)
  });
}

@NgModule({
  providers: [
    {
      provide: APOLLO_OPTIONS,
      useFactory: apolloLinkFactory,
      deps: [HttpLink]
    }
  ]
})
export class ApolloConfigModule {
}

I used my browser's dev tools and it appears that the HttpErrorResponse returned by Angular's HttpClient's does not match what Appolo Client would expect when parsing the error and calling the error handler. Here is the part of Apollo Client's code that intercepts the error and calls my error handler (you can find it at @apollo/client/link/error/index.js:11):

sub = forward(operation).subscribe({
  next: function (result) {
    // (...)
  },
  error: function (networkError) {
    retriedResult = errorHandler({
      operation: operation,
      networkError: networkError,
      //Network errors can return GraphQL errors on for example a 403
      graphQLErrors: networkError && // <-- Here my network error should be parsed to extract GraphQL errors
        networkError.result &&
        networkError.result.errors,
      forward: forward,
    });
    if (retriedResult) {
      retriedSub = retriedResult.subscribe({
        next: observer.next.bind(observer),
        error: observer.error.bind(observer),
        complete: observer.complete.bind(observer),
      });
      return;
    }
    observer.error(networkError);
  },
  complete: function () {
    // (...)                     
  },
});

The problem is the HttpErrorResponse that is emitted does not have the result field, causing graphQLErrors to be left undefined.

It worked when I tried using createHttpLink from Apollo Client instead of apollo-angular's HttpLink.create(), but then it doesn't use an Angular HttpClient which I need because I use interceptors.
Am I doing something wrong? Or should apollo-angular's HttpLinkHandler pre-parse the HttpErrorResponse so it looks more like what ApolloClient expects, instead of sending it as-is?
Thanks!