Fix unpacking undefined in listing gen

php/generate-listings.php

@@ -89,7 +89,7 @@
 
 		$listings = [];
 		foreach ($listings_raw as $id => $listing_props) {
-			$filter = [...$listing_props['rooms'], ...$listing_props['sogs']];
+			$filter = [...($listing_props['rooms'] ?? []), ...($listing_props['sogs'] ?? [])];
 			$matchees = [];
 			$rooms = CommunityRoom::select_rooms($rooms_all, $filter, $matchees);