PHP fatal error after update to 1.6.2

Hello!

After update to version 1.6.2 I got a php fatal error evertime I click on the pages overwiev.

I have the following setup:
Nginx
PHP 7.2
MariaDB 10.3.

I got this error:

2018/08/15 15:48:50 [error] 1005#1005: *65520 FastCGI sent in stderr: "PHP message: PHP Fatal error:  Uncaught Error: Call to a member function has_session() on           null in /var/www/mydomain.de/htdocs/wp-content/plugins/woocommerce-gateway-paypal-express-checkout/includes/class-wc-gateway-ppec-cart-handler.php:379
Stack trace:
#0 /var/www/mydomain.de/htdocs/wp-includes/class-wp-hook.php(286): WC_Gateway_PPEC_Cart_Handler->ensure_session(Object(WP))
#1 /var/www/mydomain.de/htdocs/wp-includes/class-wp-hook.php(310): WP_Hook->apply_filters(NULL, Array)
#2 /var/www/mydomain.de/htdocs/wp-includes/plugin.php(515): WP_Hook->do_action(Array)
#3 /var/www/mydomain.de/htdocs/wp-includes/class-wp.php(726): do_action_ref_array('wp', Array)
#4 /var/www/mydomain.de/htdocs/wp-includes/functions.php(960): WP->main(Array)
#5 /var/www/mydomain.de/htdocs/wp-admin/includes/post.php(1073): wp(Array)
#6 /var/www/mydomain.de/htdocs/wp-admin/includes/class-wp-posts-list-table.php(136): wp_edit_posts_query()
#7 /var/www/mydomain.de/htdocs/wp-admin/edit.php(180): WP_Posts_List_T" while reading response header from upstream, client: 130.180.29.186, server: timschar          ner.de, request: "GET /wp-admin/edit.php HTTP/2.0", upstream: "fastcgi://unix:/var/run/php7.2-fpm-wp-mydomain.sock:", host: "mydomain.de"