title: Mongoid::Errors::DocumentNotFound is raised even after rescuing
body: <p>I have a Rails controller with this method being triggered as a before_action:</p>
  
  <pre><code>  def authenticate_user
      Knock::AuthToken.new(token: token).entity_for(User)
    rescue Mongoid::Errors::DocumentNotFound
      render nothing: true, status: 401
    end
  </code></pre>
  
  <p>Even though I can verify that it's rescuing the error(a byebug breakpoint gets triggered under the rescue statement), it still manages to be raised immediately after:</p>
  
  <pre><code>Mongoid::Errors::DocumentNotFound (
  message:
    Document(s) not found for class User with id(s) 1.
  summary:
    When calling User.find with an id or array of ids, each parameter must match a document in the database or this error will be raised. The search was for the id(s): 1 ... (1 total) and the following ids were not found: 1.
  resolution:
    Search for an id that is in the database or set the Mongoid.raise_not_found_error configuration option to false, which will cause a nil to be returned instead of raising this error when searching for a single id, or only the matched documents when searching for multiples.):
  
  app/controllers/api/base_controller.rb:12:in `authenticate_user'
  </code></pre>
  
  <p>I've been using the rescue keyword for years in Ruby and have never encountered this.  </p>
  
  <p>What I'm running:</p>
  
  <ul>
  <li>Ruby 2.5</li>
  <li>Rails 5.2</li>
  <li>Mongoid 7.0.1</li>
  </ul>
  
  <p>Why is it that the error gets raised even when I rescue it, and how can I prevent the error from getting raised?</p>