Fix export polling missing template error (#796) (#721)

The polling controller was requesting turbo_stream format but only an
HTML template exists. Fix the Accept header to request text/html and
handle both formats in the controller.

app/controllers/family_exports_controller.rb

@@ -26,7 +26,11 @@ class FamilyExportsController < ApplicationController
       [ t("breadcrumbs.home"), root_path ],
       [ t("breadcrumbs.exports"), family_exports_path ]
     ]
-    render layout: "settings"
+
+    respond_to do |format|
+      format.html { render layout: "settings" }
+      format.turbo_stream { redirect_to family_exports_path }
+    end
   end
 
   def download

app/javascript/controllers/polling_controller.js

@@ -35,7 +35,7 @@ export default class extends Controller {
     try {
       const response = await fetch(this.urlValue, {
         headers: {
-          Accept: "text/vnd.turbo-stream.html",
+          Accept: "text/html",
           "Turbo-Frame": this.element.id,
         },
       });

test/controllers/family_exports_controller_test.rb

@@ -140,6 +140,17 @@ class FamilyExportsControllerTest < ActionDispatch::IntegrationTest
     assert_not ActiveStorage::Attachment.exists?(file_id)
   end
 
+  test "index responds to html with settings layout" do
+    get family_exports_path
+    assert_response :success
+    assert_select "title" # rendered with layout
+  end
+
+  test "index responds to turbo_stream without raising MissingTemplate" do
+    get family_exports_path, headers: { "Accept" => "text/vnd.turbo-stream.html" }
+    assert_redirected_to family_exports_path
+  end
+
   test "non-admin cannot delete export" do
     export = @family.family_exports.create!(status: "completed")
     sign_in @non_admin