router's index.js has SyntaxError

[wentiansky]

`ERROR in ./src/router/index.js
Module build failed: SyntaxError: Unexpected token (7:35)

5 |
6 | // route-level code splitting

7 | const createListView = id => () => import('../views/CreateListView').then(m => m.default(id))
| ^
8 | const ItemView = () => import('../views/ItemView.vue')
9 | const UserView = () => import('../views/UserView.vue')
10 |

@ ./src/app.js 4:0-40
@ ./src/entry-client.js

ERROR in app.850d387d367a9dc568c3.js from UglifyJs
Unexpected token: punc (,) [app.850d387d367a9dc568c3.js:95,28]`