Update app.py

app.py

@@ -47,7 +47,7 @@ def invoke(openai_api_key, prompt, agent_option):
     
             result = completion["output"]
         elif (agent_option == AGENT_LLAMAINDEX):
-            result, callback = agent_llamaindex(
+            result = agent_llamaindex(
                 config,
                 prompt
             )