Added status codes to exceptions thrown in StatusCodeSender.php, resolved error message variable undefined in StatusCodeSender.php. Updated exceptions to only retry on codes 408, 429, 500, 502, 503, and 504. Updated tests to be more consistent with each other.
Added status codes to exceptions thrown in StatusCodeSender.php, resolved error message variable undefined in StatusCodeSender.php. Updated exceptions to only retry on codes 408, 429, 500, 502, 503, and 504. Updated tests to be more consistent with each other.