Message [Class]: Update for PHP 8.1

resources/classes/message.php

@@ -33,7 +33,7 @@ if (!class_exists('message')) {
 				$mood = $mood ?: 'positive';
 				$delay = $delay ?: (1000 * (float) $_SESSION['theme']['message_delay']['text']);
 			//ignore duplicate messages
-				if (is_array($_SESSION["messages"][$mood]['message']) && @sizeof($_SESSION["messages"][$mood]['message']) != 0) {
+				if (isset($_SESSION["messages"]) && is_array($_SESSION["messages"][$mood]['message']) && @sizeof($_SESSION["messages"][$mood]['message']) != 0) {
 					if (!in_array($message, $_SESSION["messages"][$mood]['message'])) {
 						$_SESSION["messages"][$mood]['message'][] = $message;
 						$_SESSION["messages"][$mood]['delay'][] = $delay;