Enable .mjs static file fallback in all environments

framework/SimpleModule.Hosting/SimpleModuleHostExtensions.cs

@@ -188,10 +188,9 @@ public static async Task UseSimpleModuleInfrastructure(this WebApplication app)
         UseStaticFileCaching(app);
         app.MapStaticAssets();
 
-        // Fallback for dynamically generated .mjs chunks (Vite watch rebuilds)
-        // MapStaticAssets only knows about files present at build time;
-        // Vite generates new hash-named chunks at runtime that need correct MIME types
-        if (app.Environment.IsDevelopment())
+        // Fallback for .mjs chunks not in the MapStaticAssets manifest.
+        // MapStaticAssets only knows about files present at publish time;
+        // mismatched builds or Vite watch rebuilds can produce chunks it misses.
         {
             var provider = new FileExtensionContentTypeProvider();
             provider.Mappings[".mjs"] = "application/javascript";

template/SimpleModule.Host/ClientApp/app.tsx

@@ -135,8 +135,13 @@ function showErrorToast(message: string) {
 
 createInertiaApp({
   resolve: async (name) => {
-    const page = await resolvePage(name);
-    return resolveLayout(page);
+    try {
+      const page = await resolvePage(name);
+      return resolveLayout(page);
+    } catch (err) {
+      showErrorToast(`Failed to load page "${name}". Try refreshing the page.`);
+      throw err;
+    }
   },
   setup({ el, App, props }) {
     createRoot(el).render(<App {...props} />);