Fix source array is "0"

Used 'settings.options.sourceMap.filename' as 'source' value, so if wants to make source map file, 'sourceMap.filename' have to be gave with right value.

I'm not good at javascript enough and not sure this is good design.
/*!
 * node-minify
 * Copyright(c) 2011-2019 Rodolphe Stoclin
 * MIT Licensed
 */

/**
 * Module dependencies.
 */
import uglifyES from 'uglify-es';
import { utils } from '@node-minify/utils';

/**
 * Run uglifyES.
 *
 * @param {Object} settings
 * @param {String} content
 * @param {Function} callback
 */
const minifyUglifyES = ({ settings, content, callback, index }) => {
  if (settings.options.sourceMap) {
    content = { [settings.options.sourceMap.filename]: content };
  }
  const contentMinified = uglifyES.minify(content, settings.options);
  if (contentMinified.error) {
    if (callback) {
      return callback(contentMinified.error);
    }
  }
  if (contentMinified.map && settings.options.sourceMap) {
    utils.writeFile({ file: `${settings.output}.map`, content: contentMinified.map, index });
  }
  utils.writeFile({ file: settings.output, content: contentMinified.code, index });
  if (callback) {
    return callback(null, contentMinified.code);
  }
  return contentMinified.code;
};

/**
 * Expose `minifyUglifyES()`.
 */
module.exports = minifyUglifyES;

/*!
 * node-minify
 * Copyright(c) 2011-2019 Rodolphe Stoclin
 * MIT Licensed
 */

/**
 * Module dependencies.
 */
import uglifyES from 'uglify-es';
import { utils } from '@node-minify/utils';

/**
 * Run uglifyES.
 *
 * @param {Object} settings
 * @param {String} content
 * @param {Function} callback
 */
const minifyUglifyES = ({ settings, content, callback, index }) => {
  const contentMinified = uglifyES.minify(content, settings.options);
  if (contentMinified.error) {
    if (callback) {
      return callback(contentMinified.error);
    }
  }
  if (contentMinified.map && settings.options.sourceMap) {
    utils.writeFile({ file: `${settings.output}.map`, content: contentMinified.map, index });
  }
  utils.writeFile({ file: settings.output, content: contentMinified.code, index });
  if (callback) {
    return callback(null, contentMinified.code);
  }
  return contentMinified.code;
};

/**
 * Expose `minifyUglifyES()`.
 */
module.exports = minifyUglifyES;
