title: Using Bootstrap gem with Rails
body: <p>I have a fresh rails project where I only generated a controller. I've followed the directions to install bootstrap according to the bootstrap gem, and I keep getting the following error:</p>
  
  <pre><code>ActionView::Template::Error (identifier '(function(opts, pluginOpts) {return eva
  l(process' undefined):
       5:     &lt;%= csrf_meta_tags %&gt;
       6:     &lt;%= csp_meta_tag %&gt;
       7:
       8:     &lt;%= stylesheet_link_tag    'application', media: 'all', 'data-turbol
  inks-track': 'reload' %&gt;
       9:     &lt;%= javascript_include_tag 'application', 'data-turbolinks-track': '
  reload' %&gt;
      10:   &lt;/head&gt;
      11:
  
  (execjs):1
  app/views/layouts/application.html.erb:8:in `_app_views_layouts_application_html
  _erb__511219785_80461480'
  </code></pre>
  
  <p>I've followed all the instructions according to this webpage: <a href="https://github.com/twbs/bootstrap-rubygem" rel="nofollow noreferrer">https://github.com/twbs/bootstrap-rubygem</a></p>
  
  <p>My code:</p>
  
  <pre><code># Gemfile
  gem 'bootstrap', '~&gt; 4.1.1'
  gem 'jquery-rails'
  
  # app/assets/javascripts/application.js
  //= require rails-ujs
  //= require activestorage
  //= require turbolinks
  //= require jquery3
  //= require popper
  //= require bootstrap
  //= require_tree .
  
  # app/assets/stylesheets/application.scss
  @import "bootstrap";
  </code></pre>
  
  <p>Note, I also did remove *= require and *= require_tree from the application.scss and I did make sure that it's a scss file and not a css file.</p>