Reform prepopulator and allow for deletion

reform_prepopulators.rb

  collection :side_panels, form: SidePanelForm,
    prepopulator: ->(options) {
      if side_panels.count == 0
        self.side_panels << SidePanel.new(sales_order_id: sales_order_id, collection: sales_order.collection)
      end
    },
    populator: ->(fragment:, index:, **) {
      if fragment['panel_id'] == "" #'0' # or 'None' => nil then wouldn't need to make a None on the DB then.
        deserialized_panel = side_panels.find { |p| p.id.to_s == fragment["id"] }
        if deserialized_panel
          deserialized_panel.mark_for_destruction
        end
        return skip!
      end
      return skip! if side_panels[index]
      side_panels.insert(index,  sales_order.order_items.build(type: 'SidePanel', width: light_width, height: lower_height, collection: sales_order.collection))
    }