当推送到Heroku时，我们在输出中看到以下行：
...
Error detecting the assets:precompile task
...
该应用程序将成功部署，但它不会有任何资产。
这令人非常沮丧，因为没有出现错误，我们也不知道可能会发生什么。日志没有任何暗示。
这是推送的终端输出的尾部：
Your bundle is complete! It was installed into ./vendor/bundle
Cleaning up the bundler cache.
-----> Writing config/database.yml to read from DATABASE_URL
Error detecting the assets:precompile task
-----> Discovering process types
Procfile declares types -> (none)
Default types for Ruby/Rails -> console, rake, web, worker
-----> Compiled slug size: 54.8MB
-----> Launching... done, v15
http://myapp-1234.herokuapp.com deployed to Heroku
这是推送过程中完整的papertrail日志输出：
Sep 29 09:07:32 myapp-1234 heroku/slug-compiler: Slug compilation started
Sep 29 09:07:54 myapp-1234 heroku/api: Release v15 created by me@example.com
Sep 29 09:07:56 myapp-1234 heroku/slug-compiler: Slug compilation finished
Sep 29 09:08:00 myapp-1234 heroku/web.1: Process exited with status 143
Sep 29 09:08:00 myapp-1234 heroku/web.1: Starting process with command `bin/rails server -p 18025 -e staging`
Sep 29 09:08:04 myapp-1234 app/web.1: [2013-09-29 16:08:04] INFO WEBrick 1.3.1
Sep 29 09:08:05 myapp-1234 app/web.1: [2013-09-29 16:08:04] INFO ruby 2.0.0 (2013-06-27) [x86_64-linux]
Sep 29 09:08:05 myapp-1234 app/web.1: [2013-09-29 16:08:04] INFO WEBrick::HTTPServer#start: pid=2 port=18025
Sep 29 09:08:05 myapp-1234 heroku/web.1: State changed from starting to up
太棒了 - 我们什么都没学到。
在Heroku编译期间，我们可以做些什么来调试错误？