Oops, return HTTP Bad Request when item editing fails

Just a subtle thing, but Turbo can be picky about return types, and
won't reload the page with the errors in it if the status is 200.

app/controllers/items_controller.rb

@@ -124,7 +124,7 @@ class ItemsController < ApplicationController
       flash[:notice] = "\"#{@item.name}\" successfully saved!"
       redirect_to @item
     else
-      render action: "edit", layout: "application"
+      render action: "edit", layout: "application", status: :bad_request
     end
   end