我正在开发一个简单的 ruby on Rails 应用程序，但收到以下错误：
TypeError: Cannot read property 'process' of undefined (in/home/saasbook/Documents/projects/Bookkeeper/app/assets/stylesheets/application.css.sass)
提取的源码如下：
<html>
<head>
<title>Bookkeeper</title>
<%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track' => true %> //Highlighted error line in extract
<%= javascript_include_tag 'application', 'data-turbolinks-track' => true %>
<%= csrf_meta_tags %>
在我使用 Bootstrap Sass 插件添加 Bootstrap Sass 并按照此操作后，发生此错误tutorial http://www.gotealeaf.com/blog/integrating-rails-and-bootstrap-part-1/
摘录下方指出错误位于：
app/views/layouts/application.html.erb:5:in_app_views_layouts_application_html_erb__226809778_88444660'
My code
application.html.erb
<!DOCTYPE html>
<html>
<head>
<title>Bookkeeper</title>
<%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track' => true %> //Highlighted error line in extract
<%= javascript_include_tag 'application', 'data-turbolinks-track' => true %>
<%= csrf_meta_tags %>
</head>
<body>
<%= yield %>
</body>
</html>
应用程序.css.sass
/*
* This is a manifest file that'll be compiled into application.css, which will include all the files
* listed below.
*
* Any CSS and SCSS file within this directory, lib/assets/stylesheets, vendor/assets/stylesheets,
* or vendor/assets/stylesheets of plugins, if any, can be referenced here using a relative path.
*
* You're free to add application-wide styles to this file and they'll appear at the bottom of the
* compiled file so the styles you add here take precedence over styles defined in any styles
* defined in the other CSS/SCSS files in this directory. It is generally better to create a new
* file per style scope.
*
*= require_tree
*= require_self
*/
@import "bootstrap-sprockets"
@import "bootstrap"
该页面在顶部的红色边框中显示此标题，这有帮助吗？
ExecJS::ProgramError in Portal#index
