fix

app.py

@@ -1,6 +1,7 @@
 import os
 import nltk
 from functools import wraps
+import traceback
 
 # ============================ NLTK MONKEY-PATCH (MUST BE FIRST) ============================
 # This patch ensures NLTK downloads to a writable directory on platforms like Hugging Face Spaces.
@@ -181,15 +182,16 @@ def upload_files():
         traceback.print_exc()
         return jsonify({'status': 'error', 'message': f'An unexpected error occurred: {str(e)}'}), 500
 
+
 @app.route('/chat', methods=['POST'])
 def chat():
-    """Handles chat messages and streams the response."""
+    """Handles chat messages and streams the response with better error logging."""
     data = request.get_json()
     question = data.get('question')
     session_id = session.get('session_id')
 
     if not all([question, session_id]) or session_id not in rag_chains:
-        return jsonify({'status': 'error', 'message': 'Session not found or invalid. Please upload documents again.'}), 400
+        return jsonify({'status': 'error', 'message': 'Session not found. Please upload documents again.'}), 400
 
     try:
         rag_chain = rag_chains[session_id]
@@ -202,9 +204,12 @@ def chat():
         return Response(stream_with_context(generate()), mimetype='text/plain')
 
     except Exception as e:
-        print(f"Error during chat invocation: {e}")
-        return Response("An error occurred while getting the answer.", status=500, mimetype='text/plain')
-
+        # --- THIS IS THE CRUCIAL PART ---
+        print("!!! AN ERROR OCCURRED DURING CHAT STREAMING !!!")
+        traceback.print_exc() # This will print the full error to your logs
+        # Return a more specific error message to the frontend
+        error_message = f"Server error: The RAG chain failed. Check server logs for details."
+     
 # ============================ Text-to-Speech Functions ============================
 def clean_markdown_for_tts(text: str) -> str:
     """Removes markdown for cleaner text-to-speech output."""