feat: show scraper error in sidebar UI

app.py

@@ -166,11 +166,14 @@ def _scraper_thread_fn(video_id: str, redis_key: str, stop_event: threading.Even
         return
 
     logger.info("Scraper thread starting — video=%s key=%s", video_id, redis_key)
+    _META.pop("scraper_error", None)
 
     # Step 1: get the live chat ID
     live_chat_id = _get_live_chat_id(video_id, api_key)
     if not live_chat_id:
-        logger.error("Could not get live chat ID for video=%s", video_id)
+        msg = f"No active live chat found for video '{video_id}'. Make sure the stream is currently LIVE."
+        logger.error(msg)
+        _META["scraper_error"] = msg
         return
 
     logger.info("Live chat ID obtained: %s", live_chat_id)
@@ -790,6 +793,10 @@ with st.sidebar:
         status    = "running" if running else "stopped"
         st.markdown(f'<div style="font-size:0.72rem;color:{dot_color};margin-bottom:4px;">● {status}</div>', unsafe_allow_html=True)
 
+        # Show scraper error if any (only for stream A)
+        if idx == 0 and _META.get("scraper_error"):
+            st.error(_META["scraper_error"])
+
     st.divider()
 
     # ── Add / Remove stream slots ──