SCRIPT1028: Expected identifier, string or number
File: build.js, Line: 828, Column: 7

...
"use strict";
/*
 * SSR Safe Client Side ID attribute generation
 *
 */

/* harmony default export */ __webpack_exports__["a"] = ({
  props: {
    id: {
      type: String,
      default: null // This is the line of the error
    }
  },
  methods: {
    safeId: function safeId() {
      var suffix = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : '';

      var id = this.id || this.localId_ || null;
      if (!id) {
        return null;
      }
      suffix = String(suffix).replace(/s+/g, '_');
      return suffix ? id + '_' + suffix : id;
    }
  },
  computed: {
    localId_: function localId_() {
      if (!this.$isServer && !this.id && typeof this._uid !== 'undefined') {
        return '__BVID__' + this._uid;
      }
    }
  }
});
...

var path = require('path')
var webpack = require('webpack')

module.exports = {
  entry: {
    app: ['babel-polyfill','./src/main.js']
  },
...

import 'es6-promise/auto'