[philomena] use a default 'filter_id' if non is given

gallery_dl/extractor/philomena.py

@@ -46,7 +46,7 @@ class PhilomenaExtractor(BooruExtractor):
             try:
                 params["filter_id"] = INSTANCES[self.category]["filter_id"]
             except (KeyError, TypeError):
-                pass
+                params["filter_id"] = "2"
 
         while True:
             data = self.request(url, params=params).json()