JS console errors

hey guys!

I noticed there are some console errors when selecting a variation with the plugin activated.

it happens when I click on one of the variations on the product page.

here are the errors:

simulator.js?ver=2.1.2:2 Uncaught TypeError: Cannot read property 'toString' of undefined
    at HTMLBodyElement.<anonymous> (simulator.js?ver=2.1.2:2)
    at HTMLBodyElement.dispatch (jquery.js?ver=1.12.4:1)
    at HTMLBodyElement.r.handle (jquery.js?ver=1.12.4:1)
    at Object.trigger (jquery.js?ver=1.12.4:1)
    at Object.a.event.trigger (jquery-migrate.min.js?ver=1.4.1:2)
    at HTMLDivElement.<anonymous> (jquery.js?ver=1.12.4:1)
    at Function.each (jquery.js?ver=1.12.4:1)
    at a.fn.init.each (jquery.js?ver=1.12.4:1)
    at a.fn.init.trigger (jquery.js?ver=1.12.4:1)
    at HTMLFormElement.e.onFoundVariation (add-to-cart-variation.min.js?ver=3.3.3:1)

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browser: Chrome
wordpress and woocommerce on the latest version
theme: Shopkeeper

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