save_post function keeps triggering: Warning: array_map(): Argument #2 should be an array... when restoring from trash

Question

How to get a custom save_post function to return the default $post_id, $post, and $status for items with a post status of 'trash'?

Everything I return, no matter which way I try, spits out Warning: array_map(): Argument #2 should be an array in /post.php on line 1980

For items in the trash when restoring from trash or changing the post status if I play with different statuses. Seems like any return is just not returning the default array.

Need to get back to the basics here. Below is the code that works except for when restoring items from the trash, bugs out.

Thanks.

 //add_action('init', array( $this, 'init' ), 10, 2 );

add_action( 'save_post', 'update_children', 10, 2);
function update_children( $post_id, $post ) {

    if ( 'trash' != $post->post_status ){

        // Is a top level post
        if( 0 === $post->post_parent ) {
            $children = array(
                'post_parent'   => $post->ID,
                'post_type'         => 'any',   //you can use also 'any'
                'fields'            => 'ids',   // Only Return IDs
                'post_status' => 'publish',
            );
            global $post;

            if ((is_array($children))&&(!empty( $children ))){
                $the_query = new WP_Query( $children );
            }
            // The Loop
            if ( $the_query->have_posts() ) :
            while ( $the_query->have_posts() ) : $the_query->the_post();
            $pages[] = get_the_ID();
            //$pages = array();         

            if ((is_array($children))&&(!empty( $children ))) {     
                foreach( $children as $child_ids ) {
                    remove_action( 'save_post', 'update_children', 10, 2);
                    wp_update_post( $pages );
                    add_action( 'save_post', 'update_children', 10, 2);
                }           
            }
            endwhile;
            endif;      
        }
    }
}

Answer 1

So, I had to explicitly define the key value pairs to get it to work when untrashing. Not sure why it worked everywhere else though as just an array of ids.

added:

$thisupdate = array (
                    'fields'      => $pages,
                    'post_status' => 'publish'
);

wp_update_post( $thisupdate );