Error when cors is disabled on endpoint

chalice_traceback.log

Exception happened during processing of request from ('127.0.0.1', 34818)
Traceback (most recent call last):
  File "/usr/lib/python3.6/socketserver.py", line 651, in process_request_thread
    self.finish_request(request, client_address)
  File "/usr/lib/python3.6/socketserver.py", line 361, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/home/dev/jo/refunite-tasks/venv/lib/python3.6/site-packages/chalice/local.py", line 532, in __init__
    self, request, client_address, server)  # type: ignore
  File "/usr/lib/python3.6/socketserver.py", line 721, in __init__
    self.handle()
  File "/usr/lib/python3.6/http/server.py", line 418, in handle
    self.handle_one_request()
  File "/usr/lib/python3.6/http/server.py", line 406, in handle_one_request
    method()
  File "/home/dev/jo/refunite-tasks/venv/lib/python3.6/site-packages/chalice/local.py", line 553, in _generic_handle
    body=body
  File "/home/dev/jo/refunite-tasks/venv/lib/python3.6/site-packages/chalice/local.py", line 474, in handle_request
    options_headers = self._autogen_options_headers(lambda_event)
  File "/home/dev/jo/refunite-tasks/venv/lib/python3.6/site-packages/chalice/local.py", line 500, in _autogen_options_headers
    cors_headers = cors_config.get_access_control_headers()
AttributeError: 'NoneType' object has no attribute 'get_access_control_headers'