Make PHPMailer throw exceptions instead of printing them out

I successfully applied this patch and looks good to me therefore RTBC'ed!

The patch in #2 was RTBC'd 3 years ago, but no longer applies to 8.x-1.x-dev.

Checking patch smtp.module...
error: while searching for:
  $logger->info('Sending mail to: @to', array('@to' => $to));

  // Try to send e-mail. If it fails, set watchdog entry.
  if (!$mailer->Send()) {
    $logger->error('Error sending e-mail from @from to @to: @error_message', array('@from' => $from, '@to' => $to, '@error_message' => $mailer->ErrorInfo));
    return FALSE;
  }

error: patch failed: smtp.module:85
error: smtp.module: patch does not apply

Checking patch src/Plugin/Mail/SMTPMailSystem.php...
error: while searching for:
    $subject = $message['subject'];

    // Create a new PHPMailer object - autoloaded from registry.
    $mailer = new PHPMailer();

    // Turn on debugging, if requested.
    if ($this->smtpConfig->get('smtp_debugging') == 1) {

error: patch failed: src/Plugin/Mail/SMTPMailSystem.php:103
error: src/Plugin/Mail/SMTPMailSystem.php: patch does not apply

Patch from HEAD

requeued for testing

The fix for the fail that is blocking this issue is in https://www.drupal.org/project/smtp/issues/3089199#comment-13318709

re queued for testing after fixing 8.x-1.x