Newsletter - Locked Content: Call to undefined method NewsletterLock::check_user

Hi,

there is bug in Newsletter - Locket Content v1.0.1:
[11-Sep-2017 07:47:34 UTC] PHP Fatal error: Uncaught Error: Call to undefined method NewsletterLock::check_user() in /public/site/wp-content/plugins/newsletter-lock/lock.php:117

It caused by this function call:
$user = $this->check_user();

the function doesn't exists and it should be actually:
$user = Newsletter::instance()->check_user();

Please fix this in next version.

Another minor improvement what can be easily added is parsing of Tags or categories to block. If user submit something like "lock, " it creates array with two values [ 0 => "lock", 1 => "" ]. So empty post name could easily pass the condition in lock.php:L115. I suggest to strip empty strings.

Thanks,
Richard