title: Rails plugin: undefined method 'mattr_accessor' for Sentry:Module
body: <p>I'm looking at an existing Rails project and trying to see what rake tasks exist by running <code>rake -T</code>. However, when I run that I get:</p>
  
  <pre><code>(in /var/www/project)
  rake aborted!
  undefined method `mattr_accessor' for Sentry:Module
  /var/www/project/Rakefile:10
  (See full trace by running task with --trace)
  </code></pre>
  
  <p><code>vendor/plugins/sentry/tasks/sentry.rake</code> has nothing called <code>mattr_accessor</code> in it. What is this error message referring to?</p>