That bug happen since the latest update of WordPress and the error comes from Mega Main Menu plugin. We’re still waiting for Mega Main Menu Plugin update.
In this case you will need to go edit this file wp-content/plugins/mega_main_menu/src/js/frontend/menu_functions.js and then jump into line 118 and you will find this code below :
You will need to change a[href=#]:not([href=#]) to a[href=\\#]:not([href=\\#])
Anyway, i’ve been try to login into your site but it seems the username and password doesn’t correctly.