title: Rails gives hard to locate error when loading js file with syntax error
body: <p>I'm getting messages like this:</p>
  
  <pre><code>ActionView::Template::Error (Unexpected token punc «:», expected punc «,» (line: 712, col: 26, pos: 23475)
  </code></pre>
  
  <p>the stacktrace points to the manifest file (<code>application.js</code>) and doesn't provide any helpful context for locating the error. Is there a way to fix this to either provide a meaningful context or to just load the files as-is so the browser can provide the offending line number? I'm * not * using coffeescript.</p>
  
  <p>somewhat redacted app.js:</p>
  
  <pre><code>//= require_self
  //= require_tree ./services
  //= require_tree ./controllers
  //= require angular-rails-templates
  //= require_tree ../templates
  </code></pre>