Fix error message when click - after no agent left; Update code when run code value changes

app.py

@@ -171,7 +171,8 @@ def add_agent(event):
 
 
 def remove_agent(event):
-    column_agents.pop(-1)
+    if len(column_agents) > 0:
+        column_agents.pop(-1)
 
 
 btn_add.on_click(add_agent)
@@ -292,7 +293,7 @@ async def reply_chat(contents, user, instance):
         collection_name = f"{int(time.time())}_{random.randint(0, 100000)}"
         instance.collection_name = collection_name
 
-    column_agents_list = [[a.value for a in agent[0]] for agent in column_agents]
+    column_agents_list = [[a.value for a in agent[0]] for agent in column_agents]+[switch_code.value]
     if (
         not hasattr(instance, "agent_list")
         or instance.agents_list != column_agents_list