我正在尝试按照medium-angular6-heroku
的建议在heroku上部署角度应用程序但是，我在Heroku网址中说“找不到”错误。因此，使用另一种解决方案进行了修复：https://stackoverflow.com/questions/50297950/deploying-angular-app-to-heroku-build-was-successful-but-in-browser-it-shows-40
现在，我收到此错误。有人可以帮我吗？
2018-07-31T09:51:58.350527+00:00 heroku[web.1]: Starting process with command `npm start`
2018-07-31T09:52:00.485045+00:00 app[web.1]:
2018-07-31T09:52:00.485071+00:00 app[web.1]: > hello-world-app@0.0.0 start /app
2018-07-31T09:52:00.485073+00:00 app[web.1]: > node server.js
2018-07-31T09:52:00.485075+00:00 app[web.1]:
2018-07-31T09:52:00.678643+00:00 app[web.1]: listening....
2018-07-31T09:52:02.043692+00:00 heroku[web.1]: State changed from starting to up
2018-07-31T09:52:02.000000+00:00 app[api]: Build succeeded
2018-07-31T09:52:20.908340+00:00 heroku[router]: at=info method=GET path="/" host=ng-whiteboard.herokuapp.com request_id=84953bae-b5cf-422b-91ab-3adbbd083a5a fwd="103.213.201.202" dyno=web.1 connect=1ms service=24ms status=500 bytes=404 protocol=https
2018-07-31T09:52:20.909048+00:00 app[web.1]: TypeError: path must be absolute or specify root to res.sendFile
2018-07-31T09:52:20.909076+00:00 app[web.1]: at ServerResponse.sendFile (/app/node_modules/express/lib/response.js:421:11)
2018-07-31T09:52:20.909079+00:00 app[web.1]: at /app/server.js:12:7
2018-07-31T09:52:20.909081+00:00 app[web.1]: at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5)
2018-07-31T09:52:20.909083+00:00 app[web.1]: at next (/app/node_modules/express/lib/router/route.js:137:13)
2018-07-31T09:52:20.909084+00:00 app[web.1]: at Route.dispatch (/app/node_modules/express/lib/router/route.js:112:3)
2018-07-31T09:52:20.909086+00:00 app[web.1]: at Layer.handle [as handle_request] (/app/node_modules/express/lib/router/layer.js:95:5)
2018-07-31T09:52:20.909089+00:00 app[web.1]: at /app/node_modules/express/lib/router/index.js:281:22
2018-07-31T09:52:20.909090+00:00 app[web.1]: at param (/app/node_modules/express/lib/router/index.js:354:14)
2018-07-31T09:52:20.909092+00:00 app[web.1]: at param (/app/node_modules/express/lib/router/index.js:365:14)
2018-07-31T09:52:20.909093+00:00 app[web.1]: at Function.process_params (/app/node_modules/express/lib/router/index.js:410:3)
请找到我的服务器代码server.js