Hi, I'm trying to set up the ApiGateway Lambda Authorizer but it looks like it doesn't work yet

Terraform code: 
```
resource "aws_api_gateway_authorizer" "demo" {
  name                   = "demo"
  rest_api_id            = "${aws_api_gateway_rest_api.demo.id}"
  authorizer_uri         = "${aws_lambda_function.authorizer.invoke_arn}"
  authorizer_credentials = "${aws_iam_role.invocation_role.arn}"
  type = "TOKEN"
}

resource "aws_api_gateway_rest_api" "demo" {
  name = "auth-demo"
}

resource "aws_iam_role" "invocation_role" {
  name = "api_gateway_auth_invocation"
  path = "/"

  assume_role_policy = <<EOF
...
EOF
}

resource "aws_iam_role_policy" "invocation_policy" {
  name = "default"
  role = "${aws_iam_role.invocation_role.id}"

  policy = <<EOF
...
EOF
}

resource "aws_iam_role" "lambda" {
  name = "demo-lambda"

  assume_role_policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
...
}

resource "aws_lambda_function" "authorizer" {
  filename      = "${var.lambda_auth}"
  function_name = "api_gateway_authorizer"
  role          = "${aws_iam_role.lambda.arn}"
  handler       = "src/script.lambda_handler"
  runtime       = "python3.7"
  source_code_hash = "${filebase64sha256("${var.lambda_auth}")}"
}
```


I'm getting this on the debug logs:

```
Traceback (most recent call last):
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/werkzeug/serving.py", line 304, in run_wsgi
    execute(self.server.app)
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/werkzeug/serving.py", line 292, in execute
    application_iter = app(environ, start_response)
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/moto/server.py", line 132, in __call__
    return backend_app(environ, start_response)
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/app.py", line 2309, in __call__
    return self.wsgi_app(environ, start_response)
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/app.py", line 2295, in wsgi_app
    response = self.handle_exception(e)
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask_cors/extension.py", line 161, in wrapped_function
    return cors_after_request(app.make_response(f(*args, **kwargs)))
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/app.py", line 1741, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/_compat.py", line 35, in reraise
    raise value
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask_cors/extension.py", line 161, in wrapped_function
    return cors_after_request(app.make_response(f(*args, **kwargs)))
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/_compat.py", line 35, in reraise
    raise value
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/flask/app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/opt/code/localstack/.venv/lib/python3.7/site-packages/moto/core/utils.py", line 142, in __call__
    if len(result) == 3:
TypeError: object of type 'NoneType' has no len()
```

And sometimes this in terraform

`Error: error waiting for Lambda Function (api_gateway_authorizer) creation: unexpected state '', wanted target 'Active'. last error: %!s(<nil>)`

Is this feature available yet ? Thank you
except Exception as e:
        LOG.warning('Unable to run Lambda function on SNS message: %s %s' % (e, traceback.format_exc()))
def process_kinesis_records(records, stream_name):
    
    try:
        stream_arn = aws_stack.kinesis_stream_arn(stream_name)
        sources = get_event_sources(source_arn=stream_arn)
        for source in sources:
            arn = source['FunctionArn']
            event = {
                'Records': []
            }
            for rec in records:
                event['Records'].append({
                    'eventID': 'shardId-000000000000:{0}'.format(rec['sequenceNumber']),
                    'eventSourceARN': stream_arn,
                    'kinesis': rec
                })
            run_lambda(event=event, context={}, func_arn=arn)
    except Exception as e:
        LOG.warning('Unable to run Lambda function on Kinesis records: %s %s' % (e, traceback.format_exc()))
def process_sqs_message(message_body, message_attributes, queue_name, region_name=None):
    
    try:
        queue_arn = aws_stack.sqs_queue_arn(queue_name, region_name=region_name)
        sources = get_event_sources(source_arn=queue_arn)
        arns = [s.get('FunctionArn') for s in sources]
        LOG.debug('Found %s source mappings for event from SQS queue %s: %s' % (len(arns), queue_arn, arns))
        source = next(iter(sources), None)
        if source: