error in 1.7.0 and probably 1.7.1

error is [09-Jan-2018 17:56:23 America/New_York] PHP Warning: key() expects parameter 1 to be array, null given in /home/aquabarr/public_html/includes/modules/shipping/fedexwebservices.php on line 708

which in turn gives incorrect shipping estimate in the estimator to the following shipping method of USPS - check out doesn't do that but log files being written constantly.

uploaded 1.7.1 files and error persists.