message: hope speed up clean;
diff: const fs = require("fs");
  const { resolve } = require("path");
  -function clean(f) {
  +async function clean(f) {
  if (!fs.existsSync(f)) {
  return;
  }
  - const stat = fs.statSync(f);
  + const stat = await fs.promises.stat(f);
  if (stat.isDirectory()) {
  - const children = fs.readdirSync(f);
  - for (const child of children) {
  - clean(resolve(f, child));
  - }
  + const children = await fs.promises.readdir(f);
  + await Promise.all(children.map(child => clean(resolve(f, child))));
  } else {
  - fs.unlinkSync(f);
  + await fs.promises.unlink(f);
  }
  }
  