webseite/login.php

@@ -12,7 +12,7 @@ if ($_SERVER['REQUEST_METHOD'] == 'POST') {
     // Try to retrieve the user from the username
     $user = User::getFromUsername($username);
 
-    if ($user->login($password)) {
+    if ($user && $user->login($password)) {
         // Redirect to a protected page if login is successful
         header("Location: index.php?login=success");