runtime error

Exit code: 1. Reason: /lib/python3.10/site-packages/fastapi/routing.py", line 101, in app response = await f(request) File "/usr/local/lib/python3.10/site-packages/fastapi/routing.py", line 355, in app raw_response = await run_endpoint_function( File "/usr/local/lib/python3.10/site-packages/fastapi/routing.py", line 243, in run_endpoint_function return await dependant.call(**values) File "/usr/local/lib/python3.10/site-packages/gradio/routes.py", line 1720, in startup_events await app.get_blocks().run_extra_startup_events() File "/usr/local/lib/python3.10/site-packages/gradio/blocks.py", line 3143, in run_extra_startup_events await startup_event() File "/usr/local/lib/python3.10/site-packages/gradio/helpers.py", line 520, in _start_caching await self.cache() File "/usr/local/lib/python3.10/site-packages/gradio/helpers.py", line 586, in cache prediction = await self.root_block.process_api( File "/usr/local/lib/python3.10/site-packages/gradio/blocks.py", line 2250, in process_api result = await self.call_function( File "/usr/local/lib/python3.10/site-packages/gradio/blocks.py", line 1755, in call_function prediction = await fn(*processed_input) File "/usr/local/lib/python3.10/site-packages/gradio/utils.py", line 884, in async_wrapper response = await f(*args, **kwargs) File "/usr/local/lib/python3.10/site-packages/gradio/chat_interface.py", line 1076, in _examples_fn response = await anyio.to_thread.run_sync( File "/usr/local/lib/python3.10/site-packages/anyio/to_thread.py", line 61, in run_sync return await get_async_backend().run_sync_in_worker_thread( File "/usr/local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 2525, in run_sync_in_worker_thread return await future File "/usr/local/lib/python3.10/site-packages/anyio/_backends/_asyncio.py", line 986, in run result = context.run(func, *args) File "/app/app.py", line 20, in respond prompt = system_message + "\n\n" TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

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