misc: protect against removed categories (#10773)

extra/modules/root.py

@@ -840,7 +840,7 @@ class AlternateRootDirectory(OldRootDirectory):
                         uri_rest += '?' + get_request().get_query()
                 if uri_rest.startswith(base_url):
                     uri_rest = uri_rest[len(base_url):]
-                if f.category_id:
+                if f.category:
                     return redirect('%s%s/%s' % (base_url, f.category.url_name, uri_rest))
 
             raise e