Pull Request for Issue #42482.

Summary of Changes

This change addresses a fatal error encountered in the MailerFactory::createMailer method due to the cloning of a Registry object containing closures. The proposed fix involves creating a new Registry instance with the existing $defaultConfiguration instead of cloning it, effectively preventing the "Serialization of 'Closure' is not allowed" error.

Testing Instructions

$app = Factory::getApplication();

// Add a closure to the global configuration.
$closure = function() {};
$app->set('closureTest', $closure);

// Attempt to send mail using the MailerFactory.
$mail = Factory::getMailer();
$mail->clearAttachments()->clearAllRecipients();
$mail->sendMail(
    (string) $app->get('mailfrom'),
    (string) $app->get('fromname'),
    'example@example.com',
    'A test email subject!',
    'A test body.'
);

Actual result BEFORE applying this Pull Request

Attempting to send an email through certain configurations of Joomla 4.x with PHP 8.1 results in a fatal error: "Serialization of 'Closure' is not allowed".

Expected result AFTER applying this Pull Request

The fatal error is resolved, and emails can be sent successfully without encountering the "Serialization of 'Closure' is not allowed" error.

Link to documentations

• No documentation changes for docs.joomla.org needed
• No documentation changes for manual.joomla.org needed