Fatal error: Uncaught TypeError: call_user_func_array(): Argument #1 ($callback) must be a valid callback, function "kp_get_client_id" not found or invalid function name in /customers/a/e/9/startoff.uk/httpd.www/wp-includes/class-wp-hook.php:324
Stack trace:
#0 /customers/a/e/9/startoff.uk/httpd.www/wp-includes/plugin.php(205): WP_Hook->apply_filters('aec649da-4dcc-5...', Array)
#1 /customers/a/e/9/startoff.uk/httpd.www/wp-content/plugins/klarna-onsite-messaging-for-woocommerce/klarna-onsite-messaging-for-woocommerce.php(260): apply_filters('kosm_data_clien...', 'aec649da-4dcc-5...')
#2 /customers/a/e/9/startoff.uk/httpd.www/wp-content/plugins/klarna-onsite-messaging-for-woocommerce/klarna-onsite-messaging-for-woocommerce.php(80): Klarna_OnSite_Messaging_For_WooCommerce->set_data_client_id()
#3 /customers/a/e/9/startoff.uk/httpd.www/wp-includes/class-wp-hook.php(324): Klarna_OnSite_Messaging_For_WooCommerce->init('')
#4 /customers/a/e/9/startoff.uk/httpd.www/wp-includes/class-wp-hook.php(348): WP_Hook->apply_filters(NULL, Array)
#5 /customers/a/e/9/startoff.uk/httpd.www/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#6 /customers/a/e/9/startoff.uk/httpd.www/wp-settings.php(555): do_action('plugins_loaded')
#7 /customers/a/e/9/startoff.uk/httpd.www/wp-config.php(112): require_once('/customers/a/e/...')
#8 /customers/a/e/9/startoff.uk/httpd.www/wp-load.php(50): require_once('/customers/a/e/...')
#9 /customers/a/e/9/startoff.uk/httpd.www/wp-blog-header.php(13): require_once('/customers/a/e/...')
#10 /customers/a/e/9/startoff.uk/httpd.www/index.php(17): require('/customers/a/e/...')
#11 {main}
  thrown in /customers/a/e/9/startoff.uk/httpd.www/wp-includes/class-wp-hook.php on line 324