Add guard to prevent exception in Sonos Favorites (home-assistant#148854)

Author: PeteRager

homeassistant/components/sonos/favorites.py

@@ -72,7 +72,7 @@ async def async_process_event(
         """Process the event payload in an async lock and update entities."""
         event_id = event.variables["favorites_update_id"]
         container_ids = event.variables["container_update_i_ds"]
-        if not (match := re.search(r"FV:2,(\d+)", container_ids)):
+        if not container_ids or not (match := re.search(r"FV:2,(\d+)", container_ids)):
             return
 
         container_id = int(match.groups()[0])