How can you add a custom property $errorCode to a custom exception class and access it after catching?

How can you add a custom property $errorCode to a custom exception class and access it after catching?

class MyException extends Exception {
  private int $errorCode;

  public function __construct(string $message, int $code) {
    parent::__construct($message);
    $this->errorCode = $code;
  }

  public function getErrorCode(): int {
    return $this->errorCode;
  }
}

try {
  throw new MyException("Failed", 404);
} catch (MyException $e) {
  // What to echo here?
}