FIX: creating an automation without script should error (#28752)

This commit ensure we are properly showing an error to the end user and not just a vague 500.

plugins/automation/spec/system/page_objects/discourse_automation/new_automation.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+module PageObjects
+  module Pages
+    class NewAutomation < PageObjects::Pages::Base
+      def visit
+        super("/admin/plugins/discourse-automation/new")
+        self
+      end
+
+      def fill_name(name)
+        find_field("automation-name").fill_in(with: name)
+        self
+      end
+
+      def create
+        find(".create-automation").click
+        self
+      end
+
+      def has_error?(message)
+        find(".form-errors").has_text?(message)
+      end
+    end
+  end
+end