Make `is_active_sidebar` work correctly with Custom Sidebars

gistfile1.php

/**
 * This snippet will make `is_active_sidebar` work correctly with Custom Sidebars
 * @author Benjamin Intal
 */

/**
 * Gathers all the sidebar IDs and the replacement IDs. Most of this code froms from CustomSidebarsReplacer->replace_sidebars()
 */
add_action( 'cs_predetermineReplacements', 'verdant_custom_sidebars_determine_replacements' );
function verdant_custom_sidebars_determine_replacements( $defaults ) {
	global $_verdant_sidebar_ids_to_replace;
	$_verdant_sidebar_ids_to_replace = array();
	
	$customSidebarReplacer = CustomSidebarsReplacer::instance();
	
	$replacements = $customSidebarReplacer->determine_replacements( $defaults );

	foreach ( $replacements as $sb_id => $replace_info ) {

		if ( ! is_array( $replace_info ) || count( $replace_info ) < 3 ) {
			continue;
		}

		// Fix rare message "illegal offset type in isset or empty"
		$replacement = (string) @$replace_info[0];
		$replacement_type = (string) @$replace_info[1];
		$extra_index = (string) @$replace_info[2];

		$check = $customSidebarReplacer->is_valid_replacement( $sb_id, $replacement, $replacement_type, $extra_index );

		if ( $check ) {
			$_verdant_sidebar_ids_to_replace[ $sb_id ] = $replacement;
		}
	}
}


/**
 * Checks the sidebars being replaced and make corresponding is_active_sidebar calls to work
 */
add_filter( 'is_active_sidebar', 'verdant_custom_sidebars_is_active_sidebar', 10, 2 );
function verdant_custom_sidebars_is_active_sidebar( $is_active_sidebar, $index ) {
	global $_verdant_sidebar_ids_to_replace;
	
	if ( empty( $_verdant_sidebar_ids_to_replace ) ) {
		return $is_active_sidebar;
	}
	
	if ( ! empty( $_verdant_sidebar_ids_to_replace[ $index ] ) ) {
		
		// Return the current value if it's the same replacement	
		if ( $_verdant_sidebar_ids_to_replace[ $index ] == $index ) {
			return $is_active_sidebar;
		}
		
		return is_active_sidebar( $_verdant_sidebar_ids_to_replace[ $index ] );
	}
	
	return $is_active_sidebar;
}