Update app.py

app.py

@@ -32,8 +32,11 @@ def answer(user_history, bot_history, sample=True, top_p=1, temperature=0.7):
     top_p：0-1之间，生成的内容越多样
     max_new_tokens=512 lost...'''
 
-    context = "\n".join([f"用户：{user_history[i]}\n小元：{bot_history[i]}" for i in range(len(bot_history))])
-    input_text = context + "\n用户：" + user_history[-1] + "\n小元："
+    if len(bot_history)>0:
+        context = "\n".join([f"用户：{user_history[i]}\n小元：{bot_history[i]}" for i in range(len(bot_history))])
+        input_text = context + "\n用户：" + user_history[-1] + "\n小元："
+    else:
+        input_text = "用户：" + user_history[-1] + "\n小元："
     
     input_text = preprocess(input_text)
     print(input_text)