I will periodically see

--> PHP Warning: count(): Parameter must be an array or an object that implements Countable in /SITE/includes/modules/shipping/usps.php on line 492. // line 487 in an unmodified file

where that line is

$PackageSize = count($uspsQuote['Package']['Service']);

This is the else branch of $this->is_us_shipment.

Is it possible this branch needs the same check as the other branch, where we check count($uspsQuote['Package']); (line 480).