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
result = create_from_cloudformation_json_orig(resource_name, cloudformation_json, region_name)
        tags = cloudformation_json['Properties'].get('Tags', [])
        for tag in tags:
            result.tags.tag_set.tags.append(s3_models.FakeTag(tag['Key'], tag['Value']))
        return result
    create_from_cloudformation_json_orig = s3_models.FakeBucket.create_from_cloudformation_json
    s3_models.FakeBucket.create_from_cloudformation_json = Bucket_create_from_cloudformation_json
    
    def s3_key_response_post(self, request, body, bucket_name, query, key_name, *args, **kwargs):
        result = s3_key_response_post_orig(request, body, bucket_name, query, key_name, *args, **kwargs)
        s3_update_acls(self, request, query, bucket_name, key_name)
        return result
    s3_key_response_post_orig = s3_responses.S3ResponseInstance._key_response_post
    s3_responses.S3ResponseInstance._key_response_post = types.MethodType(
        s3_key_response_post, s3_responses.S3ResponseInstance)
    
    def s3_key_response_put(self, request, body, bucket_name, query, key_name, headers, *args, **kwargs):