error message on dashboard

Hi I’m getting this message on my wp dashboard can you help, I’ve been meaning to purchase the pro version of web10 but I’ve had problems in the past and I have to put it into test mode although you have sorted it in the past.

rty: stdClass::$slug in /homepages/32/d759699478/htdocs/otterboats/wp-content/plugins/tenweb-speed-optimizer/OptimizerAdmin.php on line 105