community[patch]: Handle when documents are not provided in the Cohere response (#16144)

- **Description:** This handles the cohere response when documents
aren't included in the response
  - **Issue:** N/A
  - **Dependencies:** N/A
  - **Twitter handle:** N/A

libs/community/langchain_community/retrievers/cohere_rag_retriever.py

@@ -17,10 +17,14 @@ if TYPE_CHECKING:
 
 
 def _get_docs(response: Any) -> List[Document]:
-    docs = [
+    docs = (
+        []
+        if "documents" not in response.generation_info
+        else [
             Document(page_content=doc["snippet"], metadata=doc)
             for doc in response.generation_info["documents"]
         ]
+    )
     docs.append(
         Document(
             page_content=response.message.content,