title: How does such issue is possible: an integer is being of non-numeric?
body: <pre><code>$id=intval(array['id']);
  echo ($id+1);
  
  gettype($id) : integer
  gettype($id+1) : integer
  
  PHP Warning:  A non-numeric value encountered in /var/www/html/xxxx on line xxx
  </code></pre>
  
  <p>How does is possible that integer is non-numeric?</p>
  
  <p>// PHP 7.3</p>