Uncaught Error: Call to undefined function hctpc_display_captcha_custom()

Hello

After update WP to 4.8.1 your captcha plugin (version 4.3.5) throws this error in the login widget.

Fatal error:  Uncaught Error: Call to undefined function hctpc_display_captcha_custom() in <home-dir>/wp-content/plugins/captcha/hctpc-contact-form-integration.php:12
Stack trace:
#0 <home-dir>/wp-includes/class-wp-hook.php(300): add_hctpc_captcha('')
#1 <home-dir>/wp-includes/plugin.php(203): WP_Hook->apply_filters('', Array)
#2 <home-dir>/wp-includes/general-template.php(456): apply_filters('login_form_midd...', '', Array)
#3 <home-dir>/wp-content/plugins/sidebar-login/includes/class-sidebar-login-widget.php(307): wp_login_form(Array)
#4 <home-dir>/wp-includes/class-wp-widget.php(395): Sidebar_Login_Widget->widget(Array, Array)
#5 <home-dir>/wp-includes/widgets.php(738): WP_Widget->display_callback(Array, Array)
#6 <home-dir>/wp-content/themes/WCM010013/sidebar.php(19): dynamic_sidebar('sidebar-1')
#7 <home-dir>/wp-includes/template.ph in 
<home-dir>/wp-content/plugins/captcha/hctpc-contact-form-integration.php

Thanks in advance for your help.