错误位置在 var Router = require('koa-router');  怎么会在模块这里报错

\koa-router\node_modules\koa-compose\index.js:23

  for (const fn of middleware) {

                ^^

SyntaxError: Unexpected identifier

    at exports.runInThisContext (vm.js:73:16)

    at Module._compile (module.js:443:25)

    at Object.Module._extensions..js (module.js:478:10)

    at Module.load (module.js:355:32)

    at Function.Module._load (module.js:310:12)

    at Module.require (module.js:365:17)

    at require (module.js:384:17)

    at Object.<anonymous> (node_modules\koa-router\lib\router.js:9:15)

    at Module._compile (module.js:460:26)

    at Object.Module._extensions..js (module.js:478:10)

    at Module.load (module.js:355:32)

    at Function.Module._load (module.js:310:12)

    at Module.require (module.js:365:17)

    at require (module.js:384:17)

    at Object.<anonymous> (app.js:51:14)

    at Module._compile (module.js:460:26)

    at Object.Module._extensions..js (module.js:478:10)

    at Module.load (module.js:355:32)

    at Function.Module._load (module.js:310:12)

    at Function.Module.runMain (module.js:501:10)

    at startup (node.js:129:16)

    at node.js:814:3