correction erreur php sur varibale session

sinscrire.php

 <?php
 include "functions/sinscrire.php";
 include "header.php";
-if ($_SESSION["pseudo"]!=null){
+if (isset($_SESSION['pseudo']) && $_SESSION["pseudo"]!=null){
 	echo "
 	<meta http-equiv=\"refresh\" content=\"0; url=index.php\">";
 	exit();