Java Script Error on my site

This site is having several errors and when I reported to the developer of one of the plugins, I got this response:

“I can see a JavaScript error on your site, which you can check like this:
https://smartslider.helpscoutdocs.com/article/1935-troubleshooting-with-your-browser#jserror
JavaScript errors stop every other JavaScript code on the page that should run after them and prevent them from working, so they need to be solved.

The error on your site is:
Uncaught TypeError: Cannot set property ‘_DT_CellIndex’ of undefined
and it points to the following file:
https://staging2.vamosfalarportugues.org/wp-content/uploads/siteground-optimizer-assets/siteground-optimizer-combined-js-ff119f48df74ab64ba06b24f49ce86c1.js”

In fact, when I disabled the plugin, the problems disappeared.
Now I wonder what do I need to do in order to fix it.
I enabled the plugin again so that you can see the problems such as:
smartslider3 is not running correctly
formidableforms is not supposed to open conditional fields but it is
accordion is not clickable
As soon as I disable your plugin, the problem goes away.

The page I need help with: [log in to see the link]