Script error on my site

Hello Tom,
on my website there is a script error which seems to be caused by generate press.

The error message is:
Uncaught TypeError: Cannot read property 'destroy' of undefined

I traked it down to this script:
<script>
jQuery( window ).load( function() {
jQuery( '.sf-menu .menu-item-has-children' ).GenerateDropdownMenu.destroy();
jQuery( '.sf-menu .menu-item-has-children' ).GenerateDropdownMenu({
transition_speed: 0,
open_delay: 0,
close_delay: 0
});
});
</script>

Could you help me here?