`onLogin()` silently discards Auth0 error responses

[hanifn]

Checklist

• I have looked into the Readme and the documentation, and have not found a suitable solution or answer.
• I have searched the issues and have not found a suitable solution or answer.
• I have searched the Auth0 Community forums and have not found a suitable solution or answer.
• I agree to the terms within the Auth0 Code of Conduct.

Description

When Auth0 returns an error/error_description on the login callback (expired password, breached-password block, blocked account, etc.), onLogin() redirects to / and exits with no message shown. v4's equivalent (WP_Auth0_LoginManager::die_on_login()) displayed "There was a problem with your log in: {description} [error code: {code}]".
Expected: some indication is shown to the user that login failed and why.

Reproduction

1. Trigger any Auth0-side login error (e.g. visit wp-login.php?error=access_denied&error_description=test&state=<valid-state>, or trigger a real rejection like a blocked/breached-password account).
2. Observe the browser is redirected to / with no error message, indistinguishable from a no-op.

Additional context

// line ~545-548
if (null !== $error) {
    wp_redirect('/');
    exit;
}

wp-auth0 version

5.6.1

WordPress version

7.1

PHP version

8.4