Null Given for Type String in Capitalize

[bhsmither]

In modifier.capitalize.php, an undefined argument may be provided for the $string argument.

PHP 8.1 complains about "Passing null to parameter of type string is deprecated."

This is the result of not having a default coded for Smarty variables using the capitalize modifier. Such as:

PHP:
if($variable) $Smarty->assign('VAR', $variable) // otherwise, not assigned
Template:
{$VAR|capitalize}

Suggest:

function smarty_modifier_capitalize($string = '', $uc_digits = false, $lc_rest = false)

[bhsmither]

This doesn't work as well as planned.

If passing in an actual null, PHP does not use the (empty string) default.
Suggest to test for null and change to an empty string.