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.
""" This method must be overwritten by subclasses. """
        raise Exception('Not implemented.')
    def startup(self):
        pass
    def cleanup(self, arn=None):
        pass
    def _store_logs(self, func_details, log_output, invocation_time):
        if not aws_stack.is_service_enabled('logs'):
            return
        logs_client = aws_stack.connect_to_service('logs')
        log_group_name = '/aws/lambda/%s' % func_details.name()
        time_str = time.strftime('%Y/%m/%d', time.gmtime(invocation_time))
        log_stream_name = '%s/[$LATEST]%s' % (time_str, short_uid())
        
        log_groups = logs_client.describe_log_groups()['logGroups']
        log_groups = [lg['logGroupName'] for lg in log_groups]
        if log_group_name not in log_groups:
            logs_client.create_log_group(logGroupName=log_group_name)
        
        logs_client.create_log_stream(logGroupName=log_group_name, logStreamName=log_stream_name)
        
        invocation_time = invocation_time
        finish_time = int(time.time() * 1000)
        log_lines = log_output.split('\n')
        time_diff_per_line = float(finish_time - invocation_time) / float(len(log_lines))
        log_events = []
        for i, line in enumerate(log_lines):
            if not line: