Edit History

i am triyng to solve a problem on prestashop 1.7.6.1 with custom theme, when i add to cart a product, modal cart does not show, i know the developers who created the shop and theme modified these files in custom theme >modules>ps_shoppingcart, when i click add to cart there are errors in javascript console:
core.js:28 Uncaught Error: Method hide does not exist on jQuery.modal
    at Function.error (core.js:28)
    at m.fn.init.jQuery.fn.<computed> [as modal] (custom.js:17)
    at Object.<anonymous> (theme.js:1)
    at Object.i.emit (theme.js:1)
    at Object.<anonymous> (core.js:88)
    at Object.<anonymous> (core.js:39)
    at u (core.js:39)
    at Object.fireWith [as resolveWith] (core.js:39)
    at S (core.js:39)
    at XMLHttpRequest.<anonymous> (core.js:39)

i tried to deactived a lot of addons and i updated the shopping cart addon and did a clean install but nothing, if you need addons files i can paste it here if are necessary