Comments: in `WP_Comment_Query::fill_descendants()`, `continue` if there is an empty array in the loop.

See #37416, [38297].


git-svn-id: https://develop.svn.wordpress.org/trunk@38298 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/class-wp-comment-query.php

@@ -1013,6 +1013,9 @@ class WP_Comment_Query {
 		// Prime comment caches for non-top-level comments.
 		$descendant_ids = array();
 		for ( $i = 1, $c = count( $levels ); $i <= $c; $i++ ) {
+			if ( empty( $levels[ $i ] ) ) {
+				continue;
+			}
 			$descendant_ids = array_merge( $descendant_ids, $levels[ $i ] );
 		}