fix: add missing var

Signed-off-by: Git'Fellow <12234510+solracsf@users.noreply.github.com>

Author: solracsf

apps/settings/lib/Hooks.php

@@ -123,6 +123,7 @@ public function onChangeEmail(IUser $user, $oldMailAddress) {
 			->setType('personal_settings')
 			->setAffectedUser($user->getUID());
 
+		$instanceName = $this->defaults->getName();
 		$instanceUrl = $this->urlGenerator->getAbsoluteURL('/');
 		$language = $this->languageFactory->getUserLanguage($user);
 		$l = $this->languageFactory->get('settings', $language);