Problem Navigation menu

who can help me fix this code problem. I have a white screen when open menu’s in appearence. I used the debug true log file in wp_config:

Notice: Undefined property: TF_ADMIN_MENU_WALKER::$framework in /home/vhosts/stanleybakker.nl/httpdocs/wp-includes/class-wp-walker.php on line 63

Notice: Indirect modification of overloaded property TF_ADMIN_MENU_WALKER::$framework has no effect in /home/vhosts/stanleybakker.nl/httpdocs/wp-content/themes/inshape-parent/framework/extensions/megamenu/helpers/TF_MENU_WALKER.php on line 180

Fatal error: Cannot assign by reference to overloaded object in /home/vhosts/stanleybakker.nl/httpdocs/wp-content/themes/inshape-parent/framework/extensions/megamenu/helpers/TF_MENU_WALKER.php on line 180

Thank you