Update app.py

app.py

@@ -31,12 +31,13 @@ def GenerateImageByCode(client, message, code_prompt):
     )
     run = wait_on_run(run, client, thread)
     run_steps = client.beta.threads.runs.steps.list(thread_id=thread.id, run_id=run.id, order="asc")
+    image_id = None
     for data in run_steps.model_dump()['data']:
         if "tool_calls" in data['step_details']:
             code = data['step_details']['tool_calls'][0]['code_interpreter']['input']
             if 'image' in data['step_details']['tool_calls'][0]['code_interpreter']['outputs'][0].keys():
                 image_id = data['step_details']['tool_calls'][0]['code_interpreter']['outputs'][0]['image']['file_id']
-    assert image_id
+    assert image_id is not None
     image_bytes = client.files.with_raw_response.content(image_id).content
     with open(f'{image_id}.png', 'wb') as f:
         f.write(image_bytes)