Grocery Crud Bootstrap Theme 4: every sorting, paging and filtering do not work

I have successfully installed and used Grocery Crud on a project in Codeigniter; the default theme works properly. I bought and installed the newest theme Bootstrap 4, and i have many troubles. The table is properly rendered as well as the forms for editing and inserting new rows. But every button, whatever is the action behind, is not working: no paging working, no filtering, no columns sorting. I have also tried to unset

    $crud->unset_bootstrap();
    $crud->unset_jquery();

as suggested somewhere. Any idea?

Solution from Jhon, the Grocery Crud creator

It seems that the base_url is already defined at your template and that is the error that you are getting on the chrome console. In order to solve this issue go to:

assets/grocery_crud/themes/bootstrap-v4/views/list_template.php

and change the line at around line 85:

var base_url = '';

with this (we are basically just removing the var):

base_url = '';