'toLowerCase' of undefined error in canMerge.js for css loading

Question

Getting a weird error on ng serve

styles.css - Error: styles.css from Css Minimizer
TypeError: Cannot read property 'toLowerCase' of undefined
at /Users/pavlos-mac/projects/internal_portal/internal_portal/styles.css:73837:1

node.value is undefined in canMerge.js which is part of the css loading.

const hasInherit = node => node.value.toLowerCase() === 'inherit';

Any ideas?