when I add this code I was experiencing this error

<% is_ready = !@tour.active && !@tour.price.blank? && !@tour.listing_name.blank? && !@tour.photos.blank? && !@tour.address.blank? %>

<%= form_for @tour do |f| %>
<%= f.hidden_field :active, value: true %>
<%= f.submit "Publish", id: "publish_button", class: "btn btn-normal btn-block", disabled: !is_ready %>
<% end %>