我有一个在本地运行的应用程序，基本上是发布到mailchimp。当我尝试部署到Heroku时，出现了这些错误。
2019-01-04T22:16:17.633067+00:00 app[api]: Release v4 created by user briankaty1@me.com
2019-01-04T22:16:20.218913+00:00 heroku[web.1]: Starting process with command `node app.js`
2019-01-04T22:16:22.833691+00:00 heroku[web.1]: Process exited with status 1
2019-01-04T22:16:22.853329+00:00 heroku[web.1]: State changed from starting to crashed
2019-01-04T22:16:26.779902+00:00 heroku[web.1]: Starting process with command `node app.js`
2019-01-04T22:16:29.728985+00:00 heroku[web.1]: State changed from starting to crashed
2019-01-04T22:16:29.623338+00:00 app[web.1]: internal/modules/cjs/loader.js:583
2019-01-04T22:16:29.623365+00:00 app[web.1]: throw err;
2019-01-04T22:16:29.623367+00:00 app[web.1]: ^
2019-01-04T22:16:29.623369+00:00 app[web.1]:
2019-01-04T22:16:29.623370+00:00 app[web.1]: Error: Cannot find module 'express'
2019-01-04T22:16:29.623373+00:00 app[web.1]: at Function.Module._resolveFilename (internal/modules/cjs/loader.js:581:15)
有人可以帮助我，告诉我这是什么意思吗？如果这在本地可行，就不能在Heroku上正常运行是没有意义的？
这是进行这些操作的内容。我已经安装了Express并完成了nom install，我想念什么吗？