ERROR in static/js/app.5d8e727a8dc55195c8ac.js from UglifyJs

SyntaxError: Unexpected token: keyword (default) [./src/store:1,0]

store.js

const STORAGE_KEY='todos-vuejs'
export default{
   fetch:function (){
       return window.JSON.parse(window.localStorage.getItem(STORAGE_KEY)||'[]')
   },
   save:function (items){
       window.localStorage.setItem(STORAGE_KEY,window.JSON.stringify(items))
   }
}