In the postRequest() method, you convert any 403 status code into an OutOfScope exception saying that there is a scope issue:

            if err.code == 403:
                logger.warning("Your current token scope do not allow access to %s" % topic)
                raise OutOfScope("Your current token scope do not allow access to %s" % topic) from None

However, this is too simplicistic as you can see in the official API docs: The client also could have run into issues like Maximum usage reached or some other internal issues.

Please do not discard that information when you swallow errors.