PHP warning, xmlrpc.inc line 2662: "Parameter must be an array or an object that implements Countable"

[firasd]

When upgrading our environment to PHP 7.2, we got this message filling up our error log:

PHP Warning: count(): Parameter must be an array or an object that implements Countable in /wp-content/plugins/infusionsoft-sdk/Infusionsoft/xmlrpc.inc on line 2662

From looking at other projects that implement a similar xmlrpc library, it seems the change required is to modify line 2662, from:

if(!xml_parse($parser, $data, count($data)))
to:

if(!xml_parse($parser, $data, 1))