Note that the constructor of `WP_Query` [is][1]:

    public function __construct( $query = '' ) {
		if ( ! empty( $query ) ) {
			$this->query( $query );
		}
	}

so you need non-empty input arguments in your current code snippet.


  [1]: https://github.com/WordPress/WordPress/blob/f1be128cde8f743a3c7563ceacf496a01e1cbce8/wp-includes/class-wp-query.php#L3355