Sometimes, attempting to run lambdas will return this type of error:
```
{"Type": "Server", "message": "Error executing Lambda function arn:aws:lambda:ap-northeast-1:000000000000:function:service-stage-functionName: An error occurred (ResourceAlreadyExistsException) when calling the CreateLogGroup operation: The specified log group already exists Traceback (most recent call last):\n 
File \"/opt/code/localstack/localstack/services/awslambda/lambda_api.py\", line 338, in run_lambda\n 
event, context=context, version=version, asynchronous=asynchronous)\n 
File \"/opt/code/localstack/localstack/services/awslambda/lambda_executors.py\", line 81, in execute\n 
return do_execute()\n File \"/opt/code/localstack/localstack/services/awslambda/lambda_executors.py\", line 70, in do_execute\n self._store_logs(func_details, log_output, invocation_time)\n 
File \"/opt/code/localstack/localstack/services/awslambda/lambda_executors.py\", line 105, in _store_logs\n logs_client.create_log_group(logGroupName=log_group_name)\n 
File \"/opt/code/localstack/.venv/lib/python3.6/site-packages/botocore/client.py\", line 357, in _api_call\n 
return self._make_api_call(operation_name, kwargs)\n 
File \"/opt/code/localstack/.venv/lib/python3.6/site-packages/botocore/client.py\", line 661, in _make_api_call\n 
raise error_class(parsed_response, operation_name)\n
botocore.errorfactory.ResourceAlreadyExistsException: An error occurred (ResourceAlreadyExistsException) when calling the CreateLogGroup operation: The specified log group already exists\n", "__type": "InternalFailure"}
```
I am not yet sure if there are any particular settings that cause it, since it does not occur for certain deployments.

Will update if I can figure out the exact configuration.
if isinstance(value, dict):
        if len(value) == 1 and 'Ref' in value:
            result = resolve_ref(stack_name, value['Ref'],
                resources, attribute='PhysicalResourceId')
            return result
        elif len(value) == 1 and 'Fn::GetAtt' in value:
            return resolve_ref(stack_name, value['Fn::GetAtt'][0],
                resources, attribute=value['Fn::GetAtt'][1])
        else:
            for key, val in iteritems(value):
                value[key] = resolve_refs_recursively(stack_name, val, resources)
        
        if len(value) == 1 and 'Fn::Join' in value:
            return value['Fn::Join'][0].join(value['Fn::Join'][1])
        if len(value) == 1 and 'Fn::Sub' in value:
            result = value['Fn::Sub'][0]
            for key, val in value['Fn::Sub'][1].items():
                val = resolve_refs_recursively(stack_name, val, resources)
                result = result.replace('${%s}' % key, val)
            return result
    if isinstance(value, list):
        for i in range(0, len(value)):
            value[i] = resolve_refs_recursively(stack_name, value[i], resources)
    return value