Skeletron | Computes straight skeletons of simple polygons

You aren't handling errors on the for await (const l of ss) {...} loop. When you try to run this on a directory, your for await loop will reject and since you don't catch or handle that rejection, the containing async function will also reject and the program will stop.

You can try putting a try/catch around the for await loop and see if that works. But, I've found numerous bugs in the for await feature with streams and even filed some of the bugs. The bugs occur if there are errors opening the file or errors reading the file so this feature is just buggy and I've decided not to use it in my code for this reason.

Also, note that you don't have a good way to communicate back errors from the error event since you can't reject the async function from inside that nested event handler. Overall streams and their events do not mix very well with promise-based programming. There are ways to promisify some of the stream events, but it's a work-in-progress to make streams work well with promises.