title: Exactly what causes E_CORE_ERROR and E_CORE_WARNING?
body: <p><a href="http://php.net/manual/en/errorfunc.constants.php" rel="noreferrer">PHP Manual</a> states that E_CORE_ERROR are fatal errors that occur during PHP's initial startup:</p>
  
  <blockquote>
    <p>This is like an E_ERROR, except it is generated by the core of PHP.</p>
  </blockquote>
  
  <p>Also, it states that E_CORE_WARNING are warnings that occur during PHP's initial startup:</p>
  
  <blockquote>
    <p>This is like an E_WARNING, except it is generated by the core of PHP.</p>
  </blockquote>
  
  <p>How exactly does E_CORE_ERROR and E_CORE_WARNING occur?</p>
  
  <p>Specifically, what will cause them?</p>