【WordPress】LINE Notifyにメッセージ通知する

functions.php

if ( ! function_exists( 'my_send_linenotify' ) ) {
    function my_send_linenotify( $message, $image_thumbnail = '', $image_fullsize = '' ) {
        $url = 'https://notify-api.line.me/api/notify';
        $token = '[MY_ACCESS_TOKEN]';
        $response = wp_remote_post( $url, array(
            'method' => 'POST',
            'headers' => array(
                'Authorization' => 'Bearer '.$token,
            ),
            'body' => array(
                'message' => $message,
                'imageThumbnail' => $image_thumbnail,
                'imageFullsize' => $image_fullsize,
            ),
        ));
        if ( is_wp_error( $response ) ) {
            $error_message = $response->get_error_message();
            echo "Error: $error_message";
        }
    }
}