Critical CSS 'Unknown Word' Error

Whenever I try to generate critical CSS I get errors like this for all pages:

/*CssSyntaxError: /min/cf290.css:1:6491: Unknown word*/

From doing some research, this seems like it is happening because Litespeed is coming across CSS errors. Is it possible to get better handling of CSS errors when generating critical CSS? I don't get these kinds of errors in any other plugins that generate critical CSS so it must be possible.

Start by reproducing critical CSS generation for the affected pages and inspect the reported /min/cf290.css error at position 6491. The issue does not name a source file or test, so locate the critical CSS generation entry point and determine how CSS syntax errors are currently handled; done means generation handles the reported error without failing and has coverage for it.

Written by the indexing model from the issue text.