Update app.py

app.py

@@ -172,7 +172,7 @@ def chat_with_model(prompt, document_section, model_choice='gpt-3.5-turbo'):
     for part in stream:
         chunk_message = (part.choices[0].delta.content or "")
         collected_messages.append(chunk_message)  # save the message
-        content=chunk["choices"][0].get("delta",{}).get("content")
+        content=part["choices"][0].get("delta",{}).get("content")
         try:
             report.append(content)
             if len(content) > 0: