columns works for Page, but not Resource

[seanlinsley]

Given this configuration:

ActiveAdmin.register Client do
  show do
    columns do
      column do
      end
    end
  end
end

You get this error:

NoMethodError - undefined method `span_size' for #<ActiveAdmin::Views::Panel:0x00000108801778>:
  arbre (1.0.2) lib/arbre/element.rb:182:in `method_missing'
  activeadmin-b794f4b7550d/lib/active_admin/views/components/columns.rb:105:in `block in columns_span_count'
  activeadmin-b794f4b7550d/lib/active_admin/views/components/columns.rb:105:in `columns_span_count'
  activeadmin-b794f4b7550d/lib/active_admin/views/components/columns.rb:91:in `calculate_columns!'
  activeadmin-b794f4b7550d/lib/active_admin/views/components/columns.rb:75:in `add_child'
  arbre (1.0.2) lib/arbre/element/builder_methods.rb:40:in `insert_tag'
  arbre (1.0.2) lib/arbre/element/builder_methods.rb:14:in `panel'
  app/admin/client.rb:22:in `block (3 levels) in <top (required)>'
  arbre (1.0.2) lib/arbre/element/builder_methods.rb:31:in `block in build_tag'
  arbre (1.0.2) lib/arbre/context.rb:92:in `with_current_arbre_element'
  arbre (1.0.2) lib/arbre/element/builder_methods.rb:49:in `with_current_arbre_element'
  arbre (1.0.2) lib/arbre/element/builder_methods.rb:26:in `build_tag'
  arbre (1.0.2) lib/arbre/element/builder_methods.rb:39:in `insert_tag'
  arbre (1.0.2) lib/arbre/element/builder_methods.rb:14:in `columns'
  app/admin/client.rb:21:in `block (2 levels) in <top (required)>'

Which isn't what you expect given the columns DSL on pages like the dashboard.

[bsvin33t]

Hi @seanlinsley I have created a PR for the above error. It is #3878