fix mypy

Author: leehuwuj

python/llama-index-server/llama_index/server/api/utils/chat_request.py

@@ -4,13 +4,18 @@
 
 
 def get_artifacts(chat_request: ChatRequest) -> List[Artifact]:
-    """Return a list of artifacts sorted by their creation time. Artifacts without a creation time are placed at the end."""
-    artifacts = [
-        Artifact.from_message(message)  # type: ignore
-        for message in chat_request.messages
-        if Artifact.from_message(message) is not None
-    ]
-    return sorted(artifacts, key=lambda a: (a.created_at is None, a.created_at))
+    """
+    Return a list of artifacts sorted by their creation time.
+    Artifacts without a creation time are placed at the end.
+    """
+    return sorted(
+        [
+            artifact
+            for artifact in (Artifact.from_message(m) for m in chat_request.messages)
+            if artifact is not None
+        ],
+        key=lambda a: (a.created_at is None, a.created_at),
+    )
 
 
 def get_last_artifact(chat_request: ChatRequest) -> Optional[Artifact]: