title: Can't set namespace with class extending Exception
body: <p>I have a PHP file that extends the Exception class.</p>
  
  <pre><code>namespace App\CustomException;
  
  class FileException extends Exception {
  
      public function __construct($name) {
          parent::construct($name);
      }
  }
  </code></pre>
  
  <p>I get a fatal error: <code>Fatal error: Class 'App\CustomException\Exception</code> on the line for the class that extends <code>Exception</code>. </p>
  
  <p>I want to use a namespace for my custom exception messages so that I can import them easily in a another file, like <code>use App\CustomException</code>. </p>
  
  <p>Why am I getting an error and how do I fix this? I don't get an error when I remove <code>extend Exception</code>, so I'm guessing this has something to do with the parent class.</p>