Replacing :
if ( 'gs_sim' !== $item->object ) {
with:
if (!isset($item->object) || $item->object !== 'gs_sim'){
and replacing
if ('FULL HTML OUTPUT' === $item->post_title ) {
with
if (isset($item->post_title) && 'FULL HTML OUTPUT' === $item->post_title ) {
In the file: wp-content/plugins/shortcode-in-menus/includes/class-shortcode-in-menus.php
Stops this plugin from filling the log with thousands of error lines per day.