Fix for #2363 (Handle empty response from lubimyczytac metadata provider)

cps/metadata_provider/lubimyczytac.py

@@ -113,6 +113,7 @@ class LubimyCzytac(Metadata):
     ) -> Optional[List[MetaRecord]]:
         if self.active:
             result = requests.get(self._prepare_query(title=query))
+            if result.text:
                 root = fromstring(result.text)
                 lc_parser = LubimyCzytacParser(root=root, metadata=self)
                 matches = lc_parser.parse_search_results()