Add defensive optional chaining for helmet properties

Use optional chaining (?.) when accessing helmet properties to prevent
"Cannot read property 'toString' of undefined" errors if helmet exists
but individual properties (title, link, meta, style) are undefined.

Changes applied to all server rendering files:
- react_on_rails/spec/dummy/client/app/startup/ReactHelmetApp.server.jsx
- react_on_rails/spec/dummy/client/app/startup/ReactHelmetAppBroken.server.jsx
- react_on_rails_pro/spec/dummy/client/app/ror-auto-load-components/ReactHelmetApp.server.jsx
- react_on_rails_pro/spec/dummy/client/app/loadable/loadable-server.imports-hmr.jsx
- react_on_rails_pro/spec/dummy/client/app/loadable/loadable-server.imports-loadable.jsx

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: justin808

react_on_rails/spec/dummy/client/app/startup/ReactHelmetApp.server.jsx

@@ -30,7 +30,7 @@ export default (props, _railsContext) => {
 
   const renderedHtml = {
     componentHtml,
-    title: helmet ? helmet.title.toString() : '',
+    title: helmet?.title?.toString() || '',
   };
 
   // Note that this function returns an Object for server rendering.

react_on_rails/spec/dummy/client/app/startup/ReactHelmetAppBroken.server.jsx

@@ -28,7 +28,7 @@ export default (props) => {
 
   const renderedHtml = {
     componentHtml,
-    title: helmet ? helmet.title.toString() : '',
+    title: helmet?.title?.toString() || '',
   };
   return { renderedHtml };
 };

react_on_rails_pro/spec/dummy/client/app/loadable/loadable-server.imports-hmr.jsx

@@ -19,10 +19,10 @@ const hmrApp = (props, railsContext) => {
   return {
     renderedHtml: {
       componentHtml,
-      link: helmet ? helmet.link.toString() : '',
-      meta: helmet ? helmet.meta.toString() : '',
-      style: helmet ? helmet.style.toString() : '',
-      title: helmet ? helmet.title.toString() : '',
+      link: helmet?.link?.toString() || '',
+      meta: helmet?.meta?.toString() || '',
+      style: helmet?.style?.toString() || '',
+      title: helmet?.title?.toString() || '',
     },
   };
 };

react_on_rails_pro/spec/dummy/client/app/loadable/loadable-server.imports-loadable.jsx

@@ -29,13 +29,13 @@ const loadableApp = (props, railsContext) => {
   return {
     renderedHtml: {
       componentHtml,
-      link: helmet ? helmet.link.toString() : '',
+      link: helmet?.link?.toString() || '',
       linkTags: extractor.getLinkTags(),
       styleTags: extractor.getStyleTags(),
-      meta: helmet ? helmet.meta.toString() : '',
+      meta: helmet?.meta?.toString() || '',
       scriptTags: extractor.getScriptTags(),
-      style: helmet ? helmet.style.toString() : '',
-      title: helmet ? helmet.title.toString() : '',
+      style: helmet?.style?.toString() || '',
+      title: helmet?.title?.toString() || '',
     },
   };
 };

react_on_rails_pro/spec/dummy/client/app/ror-auto-load-components/ReactHelmetApp.server.jsx

@@ -40,7 +40,7 @@ export default async (props, _railsContext) => {
 
   const promiseObject = {
     componentHtml,
-    title: helmet ? helmet.title.toString() : '',
+    title: helmet?.title?.toString() || '',
   };
   return promiseObject;
 };