grabUrlsFromLastEmail passes null to preg_match_all for single-part emails #138

grabUrlsFromLastEmail() passes $message->getTextContent() and $message->getHtmlContent() straight to preg_match_all(). mail-mime-parser returns null for a part that doesn't exist, so every single-part email triggers a deprecation notice:

Deprecated: preg_match_all(): Passing null to parameter #2 ($subject) of type string is deprecated
in src/Module/MailCatcher.php on line 282 / 285

• Plain-text-only email: no HTML part, so the notice comes from line 285.
• HTML-only email: no text part, so the notice comes from line 282.

The returned URLs are still correct today. However, test suites that turn deprecations into failures error out, and this becomes a TypeError once PHP drops the null-to-internal-parameter coercion.

Reproduction

$I->sendEmail('user@example.com', 'Subject', 'Visit https://example.com/a'); // plain-text only
$I->grabUrlsFromLastEmail(); // Deprecated: preg_match_all(): Passing null to parameter #2 ...

Expected

A missing part is treated as empty content, with no notice.