Minify: do not require MinifyWorker two times when creating a pool of two workers

src/node/utils/Minify.js

@@ -35,7 +35,8 @@ const logger = log4js.getLogger('Minify');
 
 const ROOT_DIR = path.join(settings.root, 'src/static/');
 
-const threadsPool = new Threads.Pool(() => Threads.spawn(new Threads.Worker('./MinifyWorker')), 2);
+const threadWorker = new Threads.Worker('./MinifyWorker');
+const threadsPool = new Threads.Pool(() => Threads.spawn(threadWorker), 2);
 
 const LIBRARY_WHITELIST = [
   'async',

src/node/utils/MinifyWorker.js

@@ -18,6 +18,7 @@ const compressCSS = async (filename, ROOT_DIR) => {
     const output = await new CleanCSS({
       rebase: true,
       rebaseTo: basePath,
+      returnPromise: true,
     }).minify([absPath]);
     return output.styles;
   } catch (error) {