Ensure invalid app IDs redirect properly without issues in portal

packages/builder/src/pages/builder/portal/apps/[appId]/_layout.svelte

@@ -0,0 +1,15 @@
+<script>
+  import { params, redirect } from "@roxi/routify"
+  import { apps } from "stores/portal"
+
+  $: app = $apps.find(app => app.appId === $params.appId)
+  $: {
+    if (!app) {
+      $redirect("../")
+    }
+  }
+</script>
+
+{#if app}
+  <slot />
+{/if}

packages/builder/src/pages/builder/portal/apps/[appId]/index.svelte

@@ -52,7 +52,7 @@
       Fullscreen
     </ActionButton>
   </div>
-  <iframe src={iframeUrl} />
+  <iframe src={iframeUrl} title={app.name} />
 </div>
 
 <style>