Why was my item 'MPTasks' rejected?

Five days ago, I submitted my first item to Codecanyon. Today, I’ve recived an email saying that my item was rejected:

Thanks for your submission.

After completing our review, we’ve determined that ‘MPTasks’ isn’t at the quality standard needed to continue forward with the review process on CodeCanyon. As the submission is too far off the standards we require, you’ll be unable to re-submit on this occasion.

Comments from your Quality team

  • Please make sure the code adheres to PSR standards.

  • Make sure that the code doesn’t raise any PHP errors, notices or warnings. Please set error_reporting(E_ALL)

  • Please double check for common security vulnerabilities: SQL injection, XSS, CSRF etc

  • Please make sure the item doesn’t contain any encrypted code or a third party licensing system.

If you need some help meeting our submission requirements, be sure to take advantage of Envato Tuts+ tutorials, ask for feedback from your helpful community, and check out our support article.

We’d love for you to continue honing your craft and look forward to what you can come up with next time.

Envato Market Team

What can I do to improve it and submit it?

Demo: https://demo.miguelpiedrafita.com/tasks