try to get rid of usless warnings

resources/functions.php

@@ -728,7 +728,7 @@ function format_string ($format, $data) {
 
 //get the format and use it to format the phone number
 	function format_phone($phone_number) {
-		if (strlen($_SESSION["format_phone_array"]) == 0) {
+		if ((is_string($_SESSION["format_phone_array"])) && (strlen($_SESSION["format_phone_array"]) == 0)) {
 			$_SESSION["format_phone_array"] = ""; //clear the menu
 			global $domain_uuid, $db;
 			$sql = "select * from v_vars ";
@@ -959,4 +959,4 @@ function number_pad($number,$n) {
 	return str_pad((int) $number,$n,"0",STR_PAD_LEFT);
 }
 
-?>
+?>