How can the PHP code be modified to handle cases where both language sessions do not exist?

When both language sessions do not exist, we can set a default language session to prevent any errors from occurring. This can be achieved by checking if both language sessions are empty and then setting a default language session if they are.

// Check if both language sessions do not exist
if(empty($_SESSION['language1']) && empty($_SESSION['language2'])) {
    // Set a default language session
    $_SESSION['language1'] = 'english';
}