Fix error handling in get_summary function

main.py

@@ -215,13 +215,15 @@ async def get_summary(dataset_id: str) -> str | None:
     try:
         # dataset_id = request.dataset_id
         try:
-            card_text = await async_httpx_client.get(
+            resp = await async_httpx_client.get(
                 f"https://huggingface.co/datasets/{dataset_id}/raw/main/README.md"
             )
+            if resp.status_code != 200:
+                return None
         except Exception as e:
             logger.error(e)
             return None
-        card_text = card_text.text
+        card_text = resp.text
         card = DatasetCard(card_text)
         text = card.text
         parsed_text = parse_markdown(text)