I found the explanation myself. It seems the error was triggered not by comments but by file size.

I ended up refactoring the ApexCharts options in a separate file, and that got rid of the error.

So it seems that web-pack has some issues with big configuration files (not sure exactly what), but clearly by reducing the file size it solved the issue.

Does not care about comments directly, but most likely, the comments are getting stripped at compilation so that affects the resulting file size, thus it's was an indirect effect when I played around with comments in my question above.