Fixes #3363; isset() added to prevent PHP notice in /usr/local/centreon/www/header.php

git-svn-id: http://svn.centreon.com/trunk/centreon@13379 6bcd3966-0018-0410-8128-fd23d134de7e

www/header.php

@@ -108,7 +108,7 @@
 		$centreon = $_SESSION["centreon"];
 		$oreon = $centreon;
 	}
-	if (!is_object($centreon)) {
+	if (!isset($centreon) || !is_object($centreon)) {
 		exit();
 	}