I am using the **latest** localstack docker image to test aws s3, lambda and cloudformation locally. s3 and lambda seems to be working fine but when I call cloudformation **create-stack** api it gives me a 502 BadGateway error. This is the command I am using

`aws cloudformation create-stack \
  --template-body template.yaml \
  --stack-name cfn-test \
  --parameters ParameterKey=BucketPrefix,ParameterValue=demo-bucket \
  --endpoint-url=http://localhost:4581`

This is the error I get:
`An error occurred (502) when calling the CreateStack operation (reached max retries: 4): Bad Gateway`

From docker logs I got the following error
`2019-12-31T22:12:09:ERROR:localstack.services.generic_proxy: Error forwarding request: 'str' object has no attribute 'get' Traceback (most recent call last):
  File "/opt/code/localstack/localstack/services/generic_proxy.py", line 242, in forward
    path=path, data=data, headers=forward_headers)
  File "/opt/code/localstack/localstack/services/cloudformation/cloudformation_listener.py", line 164, in forward_request
    modified_request = transform_template(req_data)
  File "/opt/code/localstack/localstack/services/cloudformation/cloudformation_listener.py", line 83, in transform_template
    if parsed.get('Transform') == 'AWS::Serverless-2016-10-31':
AttributeError: 'str' object has no attribute 'get'`

Although, when I try the **list-stacks** api it seems to be working fine
`aws --endpoint-url=http://localhost:4581 cloudformation list-stacks`

`{
    "StackSummaries": []
}`

`2019-12-31 22:10:51,865:API: 127.0.0.1 - - [31/Dec/2019 22:10:51] "GET / HTTP/1.1" 200 -`

I could not find a solution in any of the past issues or anywhere on the internet. Please assist
stack_param = get_stack_parameter(stack_name, ref)
    if stack_param is not None:
        return stack_param
    
    resource_status = {}
    if stack_name:
        resource_status = describe_stack_resource(stack_name, ref)
        if not resource_status:
            return
        attr_value = resource_status.get(attribute)
        if attr_value not in [None, '']:
            return attr_value
    elif ref in resources:
        resource_status = resources[ref]['__details__']
    
    resource_new = retrieve_resource_details(ref, resource_status, resources, stack_name)
    if not resource_new:
        return
    resource = resources.get(ref)
    resource_type = get_resource_type(resource)
    result = extract_resource_attribute(resource_type, resource_new, attribute)
    if not result:
        LOG.warning('Unable to extract reference attribute %s from resource: %s' % (attribute, resource_new))
    return result
def resolve_refs_recursively(stack_name, value, resources):
    if isinstance(value, dict):
        keys_list = list(value.keys())
        
        if keys_list == ['Ref']: