Unify usage of die(), die( '-1' ), exit();

[Presskopp]

like mentioned here I'd like to know if we want to unify the different die() calls we use:

// Don't load directly.
if ( ! defined( 'ABSPATH' ) ) {
        die( '-1' );
}

(mostly used, having a comment)

if ( ! defined( 'ABSPATH' ) ) {
        die();
}

(not having a comment), like seen in \wp-admin\link-parse-opml.php, \wp-admin\site-health-info.php

or even

if ( ! defined( 'ABSPATH' ) ) {
        exit();
}

like seen in \wp-includes\rss-functions.php

[rajinsharwar]

Based on this theory, I guess we should consider using die() everywhere instead of exit of die(-1).

Also, I don't think it's a bug, could go as a code enhancement.