anchor.diff:                  <select class="width-80 chosen-select" id="select-update-team-player" data-placeholder="选择一名队员...">
                     <option value="">请选择一名队员</option>
                     <% @users.each do |user| %>
  -                      <option value="<%= user.id %>"><%= "#{user.user_profile.username} - #{user.nickname}" %></option>
  +                      <option value="<%= user.id %>"><%= "#{user.user_profile.try(:username)} - #{user.nickname}" %></option>
                     <% end %>
   
                   </select>
  
positive.code:                 <select class="width-80 chosen-select" id="select-team-player" data-placeholder="选择一名队员...">
                    <option value="">请选择一名队员</option>
                    <% @users.each do |user| %>
                        <option value="<%= user.id %>"><%= "#{user.user_profile.username} - #{user.nickname}" %></option>
                    <% end %>
  
                  </select>
  
negative.code:                 <select class="width-25 chosen-select" id="select-create-team-leader" data-placeholder="请选择队长">
                    <option value=""></option>
                    <% @users.each do |user| %>
                        <option value="<%= user.id %>"><%= "#{user.user_profile.try(:username)} - #{user.nickname}" %></option>
                    <% end %>
                  </select>
                </div>
  