PHP error

Hi Team,
I have the following error on my website, can you please let me know how to fix it ?

PHP Error Count Location Call Stack Component
Warning preg_replace_callback(): Compilation failed: invalid range in character class at offset 22 4 wp-content/plugins/so-widgets-bundle/base/siteorigin-widget.class.php:839 preg_replace_callback()
wp-content/plugins/so-widgets-bundle/base/siteorigin-widget.class.php:839
SiteOrigin_Widget->get_instance_css()
wp-content/plugins/so-widgets-bundle/base/siteorigin-widget.class.php:721
SiteOrigin_Widget->save_css()
wp-content/plugins/so-widgets-bundle/base/siteorigin-widget.class.php:297
SiteOrigin_Widget->generate_and_enqueue_instance_styles()
wp-content/plugins/so-widgets-bundle/so-widgets-bundle.php:745
SiteOrigin_Widgets_Bundle->enqueue_active_widgets_scripts()
wp-includes/class-wp-hook.php:303
do_action(‘wp_enqueue_scripts’)
wp-includes/script-loader.php:2083
wp_enqueue_scripts()
wp-includes/class-wp-hook.php:303
do_action(‘wp_head’)
wp-includes/general-template.php:3015
wp_head()
wp-content/themes/relia-pro-master/header.php:20
load_template(‘~/wp-content/themes/relia-pro-master/header.php’)
wp-includes/template.php:716
locate_template()
wp-includes/general-template.php:48
get_header()
wp-content/themes/relia-pro-master/front-page.php:8 Plugin: so-widgets-bundle