后台做上传图片功能时出现这种报错

涉及代码 model： include Uploaders::CoverUploader[:cover]

<div class="form-group row <%= form.object.errors.include?(:cover) ? 'has-danger' : '' %>">
  <label class="col-md-2 form-control-label" for="hf-email">
    文章图片
  </label>

  <upload-image default-image-uri="<%= form.object.cover_url(:original) if form.object.cover.present? %>"  name="carousel[cover]" id="carousel_cover"></upload-image>
</div>

请教这类问题怎么处理？