Only use count() on countables

After upgrading to PHP 7.2, we noticed, with all versions of webform, ending with the latest dev version, that we now receive a PHP warning for every field value of a submitted webform.

The exact error is (repeated for every field):

Warning: count(): Parameter must be an array or an object that implements Countable in _webform_client_form_validate() (line 3105 of /oursitepath/sites/all/modules/contrib/webform/webform.module).

When reviewing http://php.net/manual/en/migration72.incompatible.php it is seen that you can no longer use count() in the scenario it's being used on line 3105.

The notes in that section state:

// Make sure a value is passed when the field is required.
// A simple call to empty() will not cut it here as some fields, like
// checkboxes, can return a valid value of '0'. Instead, check the
// length if it's a string, and the item count if it's an array. For
// radios, FALSE means that no value was submitted, so check that too.

So, it seems that this count() was being used because nothing else would work. What should we do here instead?

Thanks!