frontend-app-api: store bootstrap errors for app root

Route bootstrap finalization failures through an external store that re-enters React at app/root.children, and simplify prepared app finalization to use a success-only callback.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

packages/frontend-defaults/src/createApp.test.tsx

@@ -291,9 +291,6 @@ describe('createApp', () => {
       triggerSignInSuccess(identityApi);
     });
 
-    await expect(
-      screen.findByText(/Error in app/),
-    ).resolves.toBeInTheDocument();
     await expect(
       screen.findByText('sign-in bootstrap failed'),
     ).resolves.toBeInTheDocument();

packages/frontend-defaults/src/createApp.tsx

@@ -152,22 +152,12 @@ function PreparedAppRoot(props: {
   const [finalizedApp, setFinalizedApp] = useState<
     FinalizedSpecializedApp | undefined
   >();
-  const [bootstrapError, setBootstrapError] = useState<Error | undefined>();
 
   useEffect(
-    () => props.preparedApp.onFinalized(setFinalizedApp, setBootstrapError),
+    () => props.preparedApp.onFinalized(setFinalizedApp),
     [props.preparedApp],
   );
 
-  if (bootstrapError) {
-    return (
-      <>
-        <div>{bootstrapError.message}</div>
-        <h1>Error in app</h1>
-      </>
-    );
-  }
-
   if (!finalizedApp) {
     return bootstrapApp.element;
   }