it seems as if the request is not being retried.

• The refreshToken mutation successfully provides a new token
• This new token is then being successfully passed to the operation via the operation.setContext() function
• The then() function is being successfully called (catch does not activate)
• The request does not get retried and is being fullfilled with the same error "Signature has expired"

The idea is from How to execute an async fetch request and then retry last failed request? and is the accepted answer.

const errorLink = onError(
  ({ graphQLErrors, networkError, operation, forward }) => {
    if (graphQLErrors) {
      for (let err of graphQLErrors) {
        switch (err.message) {
          case "Signature has expired":
            return new Observable((observer) => {
              getNewToken()
                .then((token) => {
                  operation.setContext(({ headers = {} }) => {
                    return {
                      headers: {
                        ...headers,
                        authorization: `JWT ${token}`,
                      },
                    };
                  });
                })
                .then(() => {
                  const subscriber = {
                    next: observer.next.bind(observer),
                    error: observer.error.bind(observer),
                    complete: observer.complete.bind(observer),
                  };

                  forward(operation).subscribe(subscriber);
                })
                .catch((error) => {
                  // No refresh or client token available, we force user to login
                  observer.error(error);
                });
            });
        }
      }
    }
  }
);