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
tmp_dir = '%s/zipfile.%s' % (config.TMP_FOLDER, short_uid())
    mkdir(tmp_dir)
    tmp_file = '%s/%s' % (tmp_dir, LAMBDA_ZIP_FILE_NAME)
    save_file(tmp_file, zip_file_content)
    TMP_FILES.append(tmp_dir)
    lambda_details.cwd = tmp_dir
    return tmp_dir
def set_function_code(code, lambda_name, lambda_cwd=None):
    def generic_handler(event, context):
        raise ClientError(('Unable to find executor for Lambda function "%s". Note that ' +
            'Node.js, Golang, and .Net Core Lambdas currently require LAMBDA_EXECUTOR=docker') % lambda_name)
    arn = func_arn(lambda_name)
    lambda_details = arn_to_lambda[arn]
    runtime = lambda_details.runtime
    lambda_environment = lambda_details.envvars
    handler_name = lambda_details.handler or LAMBDA_DEFAULT_HANDLER
    code_passed = code
    code = code or lambda_details.code
    is_local_mount = code.get('S3Bucket') == BUCKET_MARKER_LOCAL
    zip_file_content = None
    if code_passed:
        lambda_cwd = lambda_cwd or set_archive_code(code_passed, lambda_name)
        if not is_local_mount:
            
            zip_file_content = get_zip_bytes(code_passed)
    else:
        lambda_cwd = lambda_cwd or lambda_details.cwd
    
    tmp_file = '%s/%s' % (lambda_cwd, LAMBDA_ZIP_FILE_NAME)
    if not zip_file_content: