How to use the electron-osx-sign.flatAsync function in electron-osx-sign

if (Array.isArray(buildDir)) {
      buildDir = buildDir[0];
    }

    logger.log(`Built app in "${buildDir}".`);

    if (macOSConfig.certNameInstaller) {
      const appFile = path.join(buildDir, `${commonConfig.name}.app`);
      await fs.ensureDir(commonConfig.distDir);
      const pkgFile = path.join(commonConfig.distDir, `${commonConfig.name}.pkg`);

      if (signManually) {
        await manualMacOSSign(appFile, pkgFile, commonConfig, macOSConfig);
      } else {
        await buildPkg({
          app: appFile,
          identity: macOSConfig.certNameInstaller,
          pkg: pkgFile,
          platform: 'mas',
        });
      }

      logger.log(`Built installer in "${commonConfig.distDir}".`);
    }
  } catch (error) {
    logger.error(error);
  }

  await restoreFiles(backup);
}

}: MakerOptions) {
    if (!['darwin', 'mas'].includes(targetPlatform)) {
      throw new Error(`The pkg maker only supports targetting "mas" and "darwin" builds.  You provided "${targetPlatform}"`);
    }

    const outPath = path.resolve(makeDir, `${appName}-${packageJSON.version}.pkg`);

    await this.ensureFile(outPath);

    const pkgConfig = {
      ...this.config,
      app: path.resolve(dir, `${appName}.app`),
      pkg: outPath,
      platform: targetPlatform,
    };
    await flatAsync(pkgConfig);

    return [outPath];
  }
}