偏僻的： ！预编译资产失败。(Heroku)

Question

所以，我通常不会在将应用程序部署到 heroku 时遇到任何问题，但是，在这种特定情况下，我遇到了预编译失败的错误...

这条线对我来说很突出：

remote:        NoMethodError: undefined method `[]' for nil:NilClass

但这里是完整的错误日志：

remote:        Bundle completed (9.35s)
remote:        Cleaning up the bundler cache.
remote:        Removing carrierwave (0.10.0)
remote:        Removing foreigner (1.7.4)
remote:        Removing mailboxer (0.12.5)
remote: -----> Preparing app for Rails asset pipeline
remote:        Running: rake assets:precompile
remote:        rake aborted!
remote:        NoMethodError: undefined method `[]' for nil:NilClass
remote:        (in /tmp/build_3dacd5df86a31726215c3dc3c1c22600/app/assets/stylesheets/application.css)
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/sass_functions.rb:63:in `sprockets_context'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-rails-4.0.5/lib/sass/rails/helpers.rb:23:in `asset_url'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/script/funcall.rb:113:in `_perform'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/script/node.rb:40:in `perform'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:298:in `visit_prop'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `visit'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:100:in `visit'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `block in visit_children'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `map'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `visit_children'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:109:in `block in visit_children'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:121:in `with_environment'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:108:in `visit_children'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `block in visit'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:356:in `visit_directive'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `visit'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:100:in `visit'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `block in visit_children'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `map'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:53:in `visit_children'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:109:in `block in visit_children'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:121:in `with_environment'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:108:in `visit_children'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `block in visit'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:128:in `visit_root'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/base.rb:37:in `visit'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:100:in `visit'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/visitors/perform.rb:7:in `visit'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/tree/root_node.rb:20:in `render'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/engine.rb:315:in `_render'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sass-3.2.19/lib/sass/engine.rb:262:in `render'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/sass_compressor.rb:24:in `evaluate'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/tilt-1.4.1/lib/tilt/template.rb:103:in `render'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/context.rb:197:in `block in evaluate'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/context.rb:194:in `each'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/context.rb:194:in `evaluate'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/bundled_asset.rb:25:in `initialize'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/base.rb:377:in `new'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/base.rb:377:in `build_asset'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/index.rb:94:in `block in build_asset'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/caching.rb:58:in `cache_asset'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/index.rb:93:in `build_asset'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/base.rb:287:in `find_asset'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/index.rb:61:in `find_asset'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:211:in `block in find_asset'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:257:in `benchmark'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:210:in `find_asset'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:119:in `block in compile'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:118:in `each'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/sprockets/manifest.rb:118:in `compile'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-rails-2.3.1/lib/sprockets/rails/task.rb:70:in `block (3 levels) in define'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-2.12.3/lib/rake/sprocketstask.rb:146:in `with_logger'
remote:        /tmp/build_3dacd5df86a31726215c3dc3c1c22600/vendor/bundle/ruby/2.2.0/gems/sprockets-rails-2.3.1/lib/sprockets/rails/task.rb:69:in `block (2 levels) in define'
remote:        Tasks: TOP => assets:precompile
remote:        (See full trace by running task with --trace)
remote:  !
remote:  !     Precompiling assets failed.
remote:  !
remote: 
remote:  !     Push rejected, failed to compile Ruby app
remote: 
remote: Verifying deploy...
remote: 
remote: !   Push rejected to fakename-dev.
remote: 
To git@heroku.com:fakename-dev.git
 ! [remote rejected] master -> master (pre-receive hook declined)
error: failed to push some refs to 'git@heroku.com:fakename-dev.git'

我做错了什么，我该如何解决？

干杯!

Answer 1

这是交易，我们在预编译时application.css以某种方式忽略了其他.scss文件中的错误，因此我们在本地预编译了资产，但无法在 heroku 上预编译它们。

我决定重命名application.css为application.css.scss，现在当我运行assets:precompile任务时，我遇到了与 heroku 相同的错误，这使我能够调查问题出在哪里。

这是一个缩小的 bootstrap.css 文件（来自设计者），我们团队中的一个开发人员决定通过缩进它并更改字体路径而不更改扩展名来重构.scss以获取可用的image-url和asset-url帮助程序。无论如何，我放弃所有这些并使用引导程序 gem 来修复图标问题。

总而言之，添加.scss到您的样式表中以在预编译时更快地找到问题所在。