Hi,
I had many difficulties to replace (from scratch) a webpack pipeline with a rollup pipeline.
And in order to be transparent against my current workflow I want to end up with two outputed files static/js/app.js and static/css/app.css.
Now I am able to extract the CSS ouput in its own app.css file, but it remains on the static/js/ directory.
When I put for example extract: '../css/app.css' I got the following error:

The "fileName" or "name" properties of emitted files must be strings that are neither absolute nor relative paths and do not contain invalid characters, received "../css/app.css".

What's weird is that when I use an absolute path like the following (and I deliberately changed the name): extract: '/public/static/css/app.css'
I still got the same error with the relative parent path (two dots ../):

The "fileName" or "name" properties of emitted files must be strings that are neither absolute nor relative paths and do not contain invalid characters, received "../css/app.css".

So somewhere the tool is smart enough to interpret the path, but why I'm not able to extract to a sibling or parent directory?

In the meantime, does anyone know how I can manage to get the CSS generated in that file?