[FIXED][BUG] Uncaught TypeError: Cannot read property 'length' of undefined

After updating to the latest version (5.8.3.0) I started getting these errors. Happens while I am editing one of my SCSS selectors (editing the SASS code).

Full stack trace:

Uncaught TypeError: Cannot read property 'length' of undefined
    at Object.add_final_compile_data (deps.js:1)
    at Object.apply_sass_post_css (microthemer.js:1)
    at Object.update_nodes_with_compiled_css (microthemer.js:1)
    at Object.cb15714841052260.1215060711889655 (microthemer.js:1)
    at Sass._handleWorkerMessage (sass.js:138)

After this error I am no longer able to edit any of the other selectors which I could previously (before editing this particular selector) edit without a problem.

The selector in question looks quite normal, here is the code:

#machine-types-container {
    .ct-new-columns > .ct-div-block {
        $machines-menu-width: 260px;
        padding: 0;
        &:first-child {
            width: calc((100% - 30px)*0.25);
            @media (max-width: 1024px) {
                width: $machines-menu-width;
                //width: calc((100% - 30px)*0.32);
            }
            @media (max-width: 767px) {
                display: none;
            }
        }
        &:nth-child(2) {
            width: calc((100% - 30px)*0.75);
            @media (max-width: 1024px) {
                width: calc(100% - #{$machines-menu-width} - 30px);
                //width: calc((100% - 30px)*0.68);
            }
            @media (max-width: 767px) {
                width: 100%;
            }
        }
    }
}