Comments: After [42703], make sure `$args['type']` in `paginate_comments_links()` is always defined.

Props anantajitjg.
Fixes #43299.

git-svn-id: https://develop.svn.wordpress.org/trunk@42736 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/link-template.php

@@ -2916,6 +2916,7 @@ function paginate_comments_links( $args = array() ) {
 		'total'        => $max_page,
 		'current'      => $page,
 		'echo'         => true,
+		'type'         => 'plain',
 		'add_fragment' => '#comments',
 	);
 	if ( $wp_rewrite->using_permalinks() ) {