运行报错了
 const { res } = this;
          ^

SyntaxError: Unexpected token {
    at exports.runInThisContext (vm.js:53:16)
    at Module._compile (module.js:374:25)
    at Object.Module._extensions..js (module.js:405:10)
    at Module.load (module.js:344:32)
    at Function.Module._load (module.js:301:12)
    at Module.require (module.js:354:17)
    at require (internal/module.js:12:17)
    at Object.<anonymous> (G:\html5\Koa\koa-grace\node_modules\koa\lib\application.js:11:18)
    at Module._compile (module.js:398:26)
    at Object.Module._extensions..js (module.js:405:10)
    at Module.load (module.js:344:32)
    at Function.Module._load (module.js:301:12)
    at Module.require (module.js:354:17)
    at require (internal/module.js:12:17)
    at Object.<anonymous> (G:\html5\Koa\koa-grace\src\app.js:4:13)
    at Module._compile (module.js:398:26)
