Rails bad input restyle with bootstrap initializer file

error_styler.rb

# Be sure to restart your server when you modify this file.

# Restyle how errors are shown
ActionView::Base.field_error_proc = proc do |html_tag, instance|
  html = %(<div class="field-with-errors">#{html_tag}</div>).html_safe

  form_fields = %w[textarea input select]
  elements = Nokogiri::HTML::DocumentFragment.parse(html_tag).css 'label, ' + form_fields.join(', ')
  elements.each do |element|
    next if element.attributes.include? "data-disable-error-styling"
    if element.node_name.eql? 'label'
      html = %(<div class='control-group error'>#{element}</div>)
    elsif form_fields.include? element.node_name
      html = %(<div class='control-group error'>#{element.add_class 'is-invalid'}<div class='invalid-feedback'>&nbsp;#{instance.error_message.to_a.uniq.join(', ')}</div></div>)
    end
  end
  html.html_safe
end