2FA results in 500-error

First of all: Thank you, your plugin is working well for us so far!

We now wanted to use your 2FA but got a 500-error at the page with the title: "Please verify that it’s you". Can you maybe help?

The logs say:

[19-Dec-2022 12:29:37 UTC] PHP Fatal error: Uncaught Error: Undefined constant "AUTOSAVE_INTERVAL" in .../wp-includes/script-loader.php:1804
Stack trace:

0 .../wp-includes/class-wp-hook.php(308): wp_just_in_time_script_localization()

1 .../wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters()

2 .../wp-includes/plugin.php(517): WP_Hook->do_action()

3 .../wp-includes/script-loader.php(2012): do_action()

4 .../wp-content/plugins/wp-cerber/cerber-2fa.php(472): print_head_scripts()

5 .../wp-content/plugins/wp-cerber/cerber-2fa.php(349): CRB_2FA::show_2fa_page()

6 .../wp-content/plugins/wp-cerber/cerber-load.php(1732): CRB_2FA::restrict_and_verify()

7 .../wp-content/plugins/wp-cerber/cerber-load.php(1700): cerber_restrict_user()

8 .../wp-includes/class-wp-hook.php(308): {closure}()

9 .../wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters()

10 .../wp-includes/plugin.php(517): WP_Hook->do_action()

11 .../wp-includes/pluggable.php(48): do_action()

12 .../wp-includes/user.php(3610): wp_set_current_user()

13 .../wp-includes/pluggable.php(70): _wp_get_current_user()

14 .../wp-includes/pluggable.php(1148): wp_get_current_user()

15 .../wp-content/plugins/sitepress-multilingual-cms/classes/language/Detection/CookieLanguage.php(52): is_user_logged_in()

16 .../wp-content/plugins/sitepress-multilingual-cms/classes/request-handling/wpml-request.class.php(110): WPML\Language\Detection\CookieLanguage->set()

17 .../wp-content/plugins/sitepress-multilingual-cms/sitepress.class.php(571): WPML_Request->set_language_cookie()

18 .../wp-content/plugins/sitepress-multilingual-cms/sitepress.class.php(392): SitePress->maybe_set_this_lang()

19 .../wp-includes/class-wp-hook.php(308): SitePress->init()

20 .../wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters()

21 .../wp-includes/plugin.php(517): WP_Hook->do_action()

22 .../wp-settings.php(480): do_action()

23 .../wp-config.php(90): require_once('…')

24 .../wp-load.php(50): require_once('…')

25 .../wp-blog-header.php(13): require_once('…')

26 .../index.php(17): require('…')

27 {main}

thrown in .../wp-includes/script-loader.php on line 1804