Update app.py

app.py

@@ -112,13 +112,14 @@ def format_conversation(history, system_prompt, tokenizer):
     else:
         # Fallback for base LMs without chat template
         prompt = system_prompt.strip() + "\n"
-        for msg in history:
-            if msg['role'] == 'user':
-                prompt += "User: " + msg['content'].strip() + "\n"
-            elif msg['role'] == 'assistant':
-                prompt += "Assistant: " + msg['content'].strip() + "\n"
-        if not prompt.strip().endswith("Assistant:"):
-            prompt += "Assistant: "
+        if len(history) > 0:
+            for msg in history:
+                if msg['role'] == 'user':
+                    prompt += "User: " + msg['content'].strip() + "\n"
+                elif msg['role'] == 'assistant':
+                    prompt += "Assistant: " + msg['content'].strip() + "\n"
+            if not prompt.strip().endswith("Assistant:"):
+                prompt += "Assistant: "
         return prompt
 
 def chat_response(user_msg, chat_history, system_prompt,