过去两年我在Heroku上有一个网络应用程序。然而，今天，我对应用程序的代码进行了一些更改，现在heroku日志显示了一些随机错误，其中我无法做出任何结果。
请您解释一下这个错误，我该怎么做才能纠正错误？
错误是 -
2018-04-26T18:52:42.120946+00:00 heroku[router]: at=info method=GET path="/static/css/main.css" host=nupblog.herokuapp.com request_id=13e71fe5-66b9-4f91-a7dc-8f3958b0a0ea fwd="122.161.219.232" dyno=web.1 connect=1ms service=12ms status=200 bytes=349 protocol=http
2018-04-26T18:52:42.119567+00:00 app[web.1]: {address space usage: 388780032 bytes/370MB} {rss usage: 26439680 bytes/25MB} [pid: 7|app: 0|req: 2/2] 10.43.197.68 () {50 vars in 938 bytes} [Thu Apr 26 18:52:42 2018] GET /static/css/main.css => generated 74 bytes in 11 msecs via sendfile() (HTTP/1.1 200) 7 headers in 275 bytes (0 switches on core 0)
2018-04-26T18:52:44.695195+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=nupblog.herokuapp.com request_id=c7a3cf77-9ac6-43e8-83ff-bb4b222ae53c fwd="122.161.219.232" dyno=web.1 connect=1ms service=26ms status=404 bytes=305 protocol=http
2018-04-26T18:52:44.693793+00:00 app[web.1]: {address space usage: 389332992 bytes/371MB} {rss usage: 27185152 bytes/25MB} [pid: 7|app: 0|req: 3/3] 10.43.197.68 () {50 vars in 943 bytes} [Thu Apr 26 18:52:44 2018] GET /favicon.ico => generated 233 bytes in 25 msecs (HTTP/1.1 404) 2 headers in 72 bytes (1 switches on core 0)
2018-04-26T18:57:54.527778+00:00 heroku[router]: at=info method=GET path="/" host=nupblog.herokuapp.com request_id=331dccda-dc09-495f-96d6-cfa67fed95e9 fwd="122.161.219.232" dyno=web.1 connect=0ms service=3ms status=200 bytes=3019 protocol=https
2018-04-26T18:57:54.527332+00:00 app[web.1]: {address space usage: 389332992 bytes/371MB} {rss usage: 27185152 bytes/25MB} [pid: 7|app: 0|req: 4/4] 10.13.210.115 () {52 vars in 1009 bytes} [Thu Apr 26 18:57:54 2018] GET / => generated 2938 bytes in 2 msecs (HTTP/1.1 200) 2 headers in 81 bytes (1 switches on core 0)
2018-04-26T18:57:54.867473+00:00 app[web.1]: {address space usage: 389332992 bytes/371MB} {rss usage: 27185152 bytes/25MB} [pid: 7|app: 0|req: 5/5] 10.13.210.115 () {50 vars in 946 bytes} [Thu Apr 26 18:57:54 2018] GET /static/css/main.css => generated 74 bytes in 2 msecs via sendfile() (HTTP/1.1 200) 7 headers in 275 bytes (0 switches on core 0)
2018-04-26T18:57:54.868499+00:00 heroku[router]: at=info method=GET path="/static/css/main.css" host=nupblog.herokuapp.com request_id=35797b24-5327-49be-be76-64516602c2a8 fwd="122.161.219.232" dyno=web.1 connect=0ms service=4ms status=200 bytes=349 protocol=https
2018-04-26T18:57:55.578817+00:00 heroku[router]: at=info method=GET path="/favicon.ico" host=nupblog.herokuapp.com request_id=41825f9c-6aa7-4e20-af53-fb6ff64a9f81 fwd="122.161.219.232" dyno=web.1 connect=0ms service=3ms status=404 bytes=305 protocol=https
2018-04-26T18:57:55.578316+00:00 app[web.1]: {address space usage: 389332992 bytes/371MB} {rss usage: 27185152 bytes/25MB} [pid: 7|app: 0|req: 6/6] 10.13.210.115 () {50 vars in 951 bytes} [Thu Apr 26 18:57:55 2018] GET /favicon.ico => generated 233 bytes in 2 msecs (HTTP/1.1 404) 2 headers in 72 bytes (1 switches on core 0)