Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12435] Update the comment
  [ticket/12435] purge_notifications() fails for unused notifications

phpBB/phpbb/notification/manager.php

@@ -759,6 +759,14 @@ class manager
 	* @param string $notification_type_name Type identifier of the subscription
 	*/
 	public function purge_notifications($notification_type_name)
+	{
+		// If a notification is never used, its type will not be added to the database
+		// nor its id cached. If this method is called by an extension during the
+		// purge step, and that extension never used its notifications,
+		// get_notification_type_id() will throw an exception. However,
+		// because no notification type was added to the database,
+		// there is nothing to delete, so we can silently drop the exception.
+		try
 		{
 			$notification_type_id = $this->get_notification_type_id($notification_type_name);
 
@@ -772,6 +780,11 @@ class manager
 
 			$this->cache->destroy('notification_type_ids');
 		}
+		catch (\phpbb\notification\exception $e)
+		{
+			// Continue
+		}
+	}
 
 	/**
 	* Enable all notifications of a certain type