Allow creating empty sitemap

[haegemonia76]

Is your feature request related to a problem? Please describe.
I'm currently creating a google news sitemap and currently I don't have any news posted on my website.

Is there any usecase that don't allow a sitemap to be empty ?

Is it possible to add an option to no throw an error if the stream has no data ?

sitemap.js/lib/sitemap-stream.ts

Lines 134 to 135 in 815680c

	if (!this.hasHeadOutput) {
	cb(new EmptySitemap());

sitemap.js/lib/sitemap-stream.ts

Lines 161 to 162 in 815680c

	if (!drain.length) {
	reject(new EmptyStream());

[huntharo]

I'm probably missing something here. But streamToPromise is kinda goofy.

I'd suggest not using streamToPromise at all and using import { finished } from 'stream/promises;' and await finished(stream);.

I'm guessing but I would not expect finished to throw if no data is written to the stream.

I can't think of any good reason why you have to use streamToPromise.