uncss is not processing all files in iterated pipeline

[Freakazoidberg]

Hello, please forgive me but english is not my motherlanguage ;-) i will try to describe it as good as i can.

I've written a gulp function where i create some (different) css files for some tenants. The only possibility was to return a promise so i can handle the iteration of the tenants:

function compileStyles() {
	return new Promise(function(resolve, reject) {
		for (const tenant of tenants) {
			// clean
			del(files(tenant).styles.custom.dest + "*.css", {force: true});
			// custom styles
			gulp.src(files(tenant).styles.custom.src)
				.pipe(sass().on("error", sass.logError))
				.pipe(postcss(processors))
				.pipe(rename(files().names.stylesOutputName))
				.pipe(gulp.dest(files(tenant).styles.custom.dest))
				.on("finish", () => {
					log("=> compiled custom styles for " + tenant);
				})
				.on("error", reject);
			// amp styles
			gulp.src(files(tenant).styles.amp.src)
				.pipe(sass().on("error", sass.logError))
				.pipe(postcss(processorsAmp))
				.pipe(replace(regexReplaceImportant, ""))
				.pipe(replace(regexReplaceCharset, ""))
				.pipe(inject.append("IR_END/"))
				.pipe(rename(files(tenant).names.stylesAmpOutputName))
				.pipe(gulp.dest(files(tenant).styles.amp.dest))
				.on("finish", () => {
					log("=> compiled amp styles for " + tenant);
				})
				.on("error", reject)
				.on("end", resolve);
		}
	});
}

It works great, even in other functions with other plugins. Except with uncss. The second block for generating the amp-stylesheets is creating my files for the tenants correctly, but only one of them is processed by the uncss module. It seems it's only the last entry of my tenants-array.

Maybe it has a complication with my wrapped promise, as i can see in the module it handles with promises for multiple files too. Is there any suggestion i can solve this problem?

	"gulp-postcss": "^9.0.0",
	"gulp-sass": "^4.1.0",
	"postcss-uncss": "^0.17.0",
	"uncss": "^0.17.3"

Thanks in advance,
regards Roman

[Freakazoidberg]

This is fixed with this undeployed commit: #431 (comment)

I've tested it with a local master-branch (it works :-) ), but would appreciate it as an npm-package. my buildserver won't get it otherwise.
please help me soon ;-)

regards Roman