Cleaner way to handle when documents is empty

Co-authored-by: Stefano Fiorucci <[email protected]>

integrations/fastembed/src/haystack_integrations/components/rankers/fastembed/ranker.py

@@ -161,9 +161,8 @@ def run(self, query: str, documents: List[Document], top_k: Optional[int] = None
             msg = "No query provided"
             raise ValueError(msg)
 
-        if documents.count == 0:
-            msg = "No documents provided"
-            raise ValueError(msg)
+        if not documents:
+            return {"documents": []}
 
         top_k = top_k or self.top_k
         if top_k <= 0: