Variation Button

When i click the Size variation and that is not function at all and there is error coming out when i check at inspect.

Below the error shown at inspect :

Uncaught TypeError: Cannot read property ‘touches’ of undefined
at $.SmartMenus.docTouchStart (jquery.smartmenus.js?ver=4.9.5:346)
at HTMLDocument.d (jquery.js?ver=1.12.4:2)
at HTMLDocument.dispatch (jquery.js?ver=1.12.4:3)
at HTMLDocument.r.handle (jquery.js?ver=1.12.4:3)
at Object.trigger (jquery.js?ver=1.12.4:3)
at Object.a.event.trigger (jquery-migrate.min.js?ver=1.4.1:2)
at HTMLSelectElement.<anonymous> (jquery.js?ver=1.12.4:3)
at Function.each (jquery.js?ver=1.12.4:2)
at a.fn.init.each (jquery.js?ver=1.12.4:2)
at a.fn.init.trigger (jquery.js?ver=1.12.4:3)
2jquery.smartmenus.js?ver=4.9.5:346 Uncaught TypeError: Cannot read property ‘touches’ of undefined
at $.SmartMenus.docTouchStart (jquery.smartmenus.js?ver=4.9.5:346)
at HTMLDocument.d (jquery.js?ver=1.12.4:2)
at HTMLDocument.dispatch (jquery.js?ver=1.12.4:3)
at HTMLDocument.r.handle (jquery.js?ver=1.12.4:3)
at Object.trigger (jquery.js?ver=1.12.4:3)
at Object.a.event.trigger (jquery-migrate.min.js?ver=1.4.1:2)
at HTMLSelectElement.<anonymous> (jquery.js?ver=1.12.4:3)
at Function.each (jquery.js?ver=1.12.4:2)
at a.fn.init.each (jquery.js?ver=1.12.4:2)
at a.fn.init.trigger (jquery.js?ver=1.12.4:3)
docTouchStart @ jquery.smartmenus.js?ver=4.9.5:346
d @ jquery.js?ver=1.12.4:2
dispatch @ jquery.js?ver=1.12.4:3
r.handle @ jquery.js?ver=1.12.4:3
trigger @ jquery.js?ver=1.12.4:3
a.event.trigger @ jquery-migrate.min.js?ver=1.4.1:2
(anonymous) @ jquery.js?ver=1.12.4:3
each @ jquery.js?ver=1.12.4:2
each @ jquery.js?ver=1.12.4:2
trigger @ jquery.js?ver=1.12.4:3
(anonymous) @ frontend.min.js?ver=1.0.19:1
dispatch @ jquery.js?ver=1.12.4:3
r.handle @ jquery.js?ver=1.12.4:3