async function manifest() {
  const base = JSON.parse(await fs.readFile(`${DIST}/manifest.json`, 'utf8'));
  const data = await buildManifest(base);
  await fs.mkdir(DIST).catch(() => {});
  await fs.writeFile(`${DIST}/manifest.json`, JSON.stringify(data), 'utf8');
}
manifest is already handled in ListBackgroundScriptsPlugin

This task is only used to tweak dist/manifest.json without rebuilding