I just bought and installed the Regn Theme. Installation was successful but when I initiated copying demo content (Conference content), the installation broke and I received the following error:

`
WordPress-Version 5.9.1
Active Theme: Regn (Version 1.2.3)
Active Plugin: (Version )
PHP-Version 7.4.3

Failure Details
==============
Ein Fehler vom Typ E_ERROR wurde in der Zeile 11 der Datei/var/www/html/wp-content/themes/reg>
hp verursacht. Fehlermeldung: Uncaught Error: Class ‘WP_Customize_Panel’ not found in/var/www>
hp:11
Stack trace:
#0/var/www/html/wp-content/themes/regn/includes/codeless_customizer/codeless_customizer_con
fig.php(148): require_once()
#1 /var/www/html/wp-includes/class-wp-hook.php(307):
CodelessCustomizerConfig->load_custom_panel()
#2 /var/www/html/wp-includes/plugin.php(189): WP_Hook->apply_filters()
#3/var/www/html/wp-content/plugins/kirki/packages/kirki-framework/compatibility/src/depreca
ted/filters.php(37): apply_filters()
#4 /var/www/html/wp-includes/class-wp-hook.php(307):
Kirki\Compatibility\Deprecated->{closure}()
#5 /var/www/html/wp-includes/plugin.php(189): WP_Hook->apply_filters()
#6/var/www/html/wp-content/plugins/kirki/packages/kirki-framework/module-panels/src/Panel.p
hp(60): apply_filters()
#7/var/www/html/wp-content/plugins/kirki/packages/kirki-framework/compatibility/src/Kirki.p
hp(132): Kirki\Panel->__construct()
#8 /var/www/html/wp-content/
`