fix retrieve documents error for search without reranker

climateqa/engine/chains/retrieve_documents.py

@@ -477,8 +477,10 @@ async def retrieve_documents(
                 docs_question_dict[key] = rerank_and_sort_docs(reranker,docs_question_dict[key],question)
     else:
         # Add a default reranking score
-        for doc in docs_question:
-            doc.metadata["reranking_score"] = doc.metadata["similarity_score"]
+        for key in docs_question_dict.keys():
+            if isinstance(docs_question_dict[key], list) and len(docs_question_dict[key]) > 0:
+                for doc in docs_question_dict[key]:
+                    doc.metadata["reranking_score"] = doc.metadata["similarity_score"]
     
     # Keep the right number of documents    
     docs_question, images_question = concatenate_documents(index, source_type, docs_question_dict, k_by_question, k_summary_by_question, k_images_by_question)