General: Validate input of wp_list_pluck().

`wp_list_pluck()` is used by WordPress to pluck items from a list. Of course, this requires a list. This validates the input of `wp_list_pluck()` to ensure it is a list.

This matches the behaviour of `wp_list_sort()` and `wp_filter_object_list()`.

Props marv2, davidbaumwald, mkox, SergeyBiryukov, dd32.
Fixes #54751.



git-svn-id: https://develop.svn.wordpress.org/trunk@53045 602fd350-edb4-49c9-b593-d223f7449a82

Author: peterwilsoncc

src/wp-includes/functions.php

@@ -5176,6 +5176,10 @@ function wp_list_filter( $list, $args = array(), $operator = 'AND' ) {
  *               `$list` will be preserved in the results.
  */
 function wp_list_pluck( $list, $field, $index_key = null ) {
+	if ( ! is_array( $list ) ) {
+		return array();
+	}
+
 	$util = new WP_List_Util( $list );
 
 	return $util->pluck( $field, $index_key );