How to use the hexo-util.deepMerge function in hexo-util

const configPath = isAbsolute(paths[i]) ? paths[i] : join(base, paths[i]);

    if (!fs.existsSync(configPath)) {
      log.w(`Config file ${paths[i]} not found.`);
      continue;
    }

    // files read synchronously to ensure proper overwrite order
    const file = fs.readFileSync(configPath);
    const ext = extname(paths[i]).toLowerCase();

    if (ext === '.yml') {
      combinedConfig = deepMerge(combinedConfig, yml.load(file));
      count++;
    } else if (ext === '.json') {
      combinedConfig = deepMerge(combinedConfig, yml.safeLoad(file, {json: true}));
      count++;
    } else {
      log.w(`Config file ${paths[i]} not supported type.`);
    }
  }

  if (count === 0) {
    log.e('No config files found. Using _config.yml.');
    return defaultPath;
  }

  log.i('Config based on', count, 'files');

  const multiconfigRoot = outputDir || base;
  const outputPath = join(multiconfigRoot, '_multiconfig.yml');

let combinedConfig = {};
  let count = 0;
  for (let i = 0; i < numPaths; i++) {
    const configPath = isAbsolute(paths[i]) ? paths[i] : join(base, paths[i]);

    if (!fs.existsSync(configPath)) {
      log.w(`Config file ${paths[i]} not found.`);
      continue;
    }

    // files read synchronously to ensure proper overwrite order
    const file = fs.readFileSync(configPath);
    const ext = extname(paths[i]).toLowerCase();

    if (ext === '.yml') {
      combinedConfig = deepMerge(combinedConfig, yml.load(file));
      count++;
    } else if (ext === '.json') {
      combinedConfig = deepMerge(combinedConfig, yml.safeLoad(file, {json: true}));
      count++;
    } else {
      log.w(`Config file ${paths[i]} not supported type.`);
    }
  }

  if (count === 0) {
    log.e('No config files found. Using _config.yml.');
    return defaultPath;
  }

  log.i('Config based on', count, 'files');

}).then(config => {
    if (!config || typeof config !== 'object') return;

    ctx.log.debug('Config loaded: %s', magenta(tildify(configPath)));

    ctx.config = deepMerge(ctx.config, config);
    config = ctx.config;

    ctx.config_path = configPath;

    config.root = config.root.replace(/\/*$/, '/');
    config.url = config.url.replace(/\/+$/, '');

    ctx.public_dir = resolve(baseDir, config.public_dir) + sep;
    ctx.source_dir = resolve(baseDir, config.source_dir) + sep;
    ctx.source = new Source(ctx);

    if (!config.theme) return;

    config.theme = config.theme.toString();
    ctx.theme_dir = join(baseDir, 'themes', config.theme) + sep;
    ctx.theme_script_dir = join(ctx.theme_dir, 'scripts') + sep;