Traceback (most recent call last):
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/bin/bentoml", line 8, in <module>
    sys.exit(cli())
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/click/core.py", line 1137, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/bentoml/cli/deployment.py", line 316, in create
    yatai_service,
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/bentoml/yatai/python_api.py", line 296, in create_deployment
    apply_response = apply_deployment(deployment_dict, yatai_service)
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/bentoml/yatai/python_api.py", line 343, in apply_deployment
    ApplyDeploymentRequest(deployment=deployment_pb)
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/bentoml/yatai/yatai_service_impl.py", line 118, in ApplyDeployment
    response = operator.apply(request.deployment, self, previous_deployment)
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/bentoml/deployment/aws_lambda/__init__.py", line 188, in apply
    prev_deployment,
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/bentoml/deployment/aws_lambda/__init__.py", line 278, in _apply
    validate_lambda_template(template_file_path)
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/bentoml/deployment/aws_lambda/utils.py", line 156, in validate_lambda_template
    validator.is_valid()
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/samcli/commands/validate/lib/sam_template_validator.py", line 60, in is_valid
    template = sam_translator.translate(sam_template=self.sam_template, parameter_values={})
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/samtranslator/translator/translator.py", line 67, in translate
    deployment_preference_collection = DeploymentPreferenceCollection()
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/samtranslator/model/preferences/deployment_preference_collection.py", line 41, in __init__
    self.codedeploy_iam_role = self._codedeploy_iam_role()
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/samtranslator/model/preferences/deployment_preference_collection.py", line 99, in _codedeploy_iam_role
    ArnGenerator.generate_aws_managed_policy_arn('service-role/AWSCodeDeployRoleForLambda')
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/samtranslator/translator/arn_generator.py", line 29, in generate_aws_managed_policy_arn
    return 'arn:{}:iam::aws:policy/{}'.format(ArnGenerator.get_partition_name(),
  File "/Users/ericyang/miniconda3/envs/test-env-bentoml/lib/python3.7/site-packages/samtranslator/translator/arn_generator.py", line 49, in get_partition_name
    region_string = region.lower()
AttributeError: 'NoneType' object has no attribute 'lower'