User profile breaks after trying to follow user

[dchandekstark]

Completed 500 Internal Server Error in 415ms

ActionView::Template::Error (undefined method `login' for #<User:0x0000000794e560>):
    12:       <h3>Follower(s)</h3>
    13:       <ul>
    14:       <% @followers.each do |f| %>
    15:         <li> <a href="<%= sufia.profile_path(f.login) %>" title="View user's profile"><%= f.name %></a></li>
    16:       <% end %>
    17:       </ul>
    18:     <%else%>
  activemodel (4.0.3) lib/active_model/attribute_methods.rb:439:in `method_missing'
  activerecord (4.0.3) lib/active_record/attribute_methods.rb:155:in `method_missing'
  acts_as_follower (0.2.1) lib/acts_as_follower/follower.rb:96:in `method_missing'
  acts_as_follower (0.2.1) lib/acts_as_follower/followable.rb:54:in `method_missing'
  /home/hydra/.rvm/gems/ruby-2.0.0-p451@course-assets/bundler/gems/sufia-93b5bc370aac/app/views/users/_follower_modal.html.erb:15:in `block in __home_hydra__rvm_gems_ruby_______p____course_assets_bundler_gems_sufia___b_bc___aac_app_views_users__follower_modal_html_erb___2123374920690985821_66349160'