fix: resolve act warnings and prevent runtime crashes on empty data

frontend/jest.setup.ts

@@ -191,6 +191,6 @@ global.fetch = jest.fn().mockImplementation((url: string) => {
   return Promise.resolve({
     ok: true,
     status: 200,
-    json: () => Promise.resolve({}),
+    json: () => Promise.resolve({ success: true, data: [] }),
   });
 });

frontend/src/pages/AITagging/AITagging.tsx

@@ -35,7 +35,7 @@ export const AITagging = () => {
     } else if (imagesError) {
       dispatch(hideLoader());
     } else if (imagesSuccess) {
-      const images = imagesData?.data as Image[];
+      const images = (imagesData?.data ?? []) as Image[];
       dispatch(setImages(images));
       dispatch(hideLoader());
     }

frontend/src/pages/Home/Home.tsx

@@ -40,7 +40,7 @@ export const Home = () => {
 
   useEffect(() => {
     if (!isSearchActive && isSuccess) {
-      const images = data?.data as Image[];
+      const images = (data?.data ?? []) as Image[];
       dispatch(setImages(images));
     }
   }, [data, isSuccess, dispatch, isSearchActive]);

frontend/src/pages/Home/MyFav.tsx

@@ -42,7 +42,7 @@ export const MyFav = () => {
   // Handle fetching lifecycle
   useEffect(() => {
     if (!isSearchActive && isSuccess) {
-      const images = data?.data as Image[];
+      const images = (data?.data ?? []) as Image[];
       dispatch(setImages(images));
     }
   }, [data, isSuccess, dispatch, isSearchActive]);

frontend/src/pages/__tests__/PageSanity.test.tsx

@@ -1,4 +1,4 @@
-import { render, screen } from '@/test-utils';
+import { render, screen, act } from '@/test-utils';
 import { Home } from '../Home/Home';
 import Settings from '../SettingsPage/Settings';
 
@@ -15,8 +15,11 @@ describe('Page Sanity Tests', () => {
   });
 
   describe('Settings Page', () => {
-    test('renders settings page sections', () => {
+    test('renders settings page sections', async () => {
       render(<Settings />);
+      await act(async () => {
+        await new Promise((resolve) => setTimeout(resolve, 0));
+      });
 
       expect(screen.getByText('Folder Management')).toBeInTheDocument();
       expect(screen.getByText('User Preferences')).toBeInTheDocument();
@@ -26,6 +29,6 @@ describe('Page Sanity Tests', () => {
         screen.getByRole('button', { name: /Check for Updates/i }),
       ).toBeInTheDocument();
       expect(screen.getByText('GPU Acceleration')).toBeInTheDocument();
-    }); // Settings is expected to render synchronously.
+    });
   });
 });

frontend/src/pages/__tests__/SettingsPage.test.tsx

@@ -1,19 +1,22 @@
-import { render, screen } from '@/test-utils';
+import { render, screen, act } from '@/test-utils';
 import userEvent from '@testing-library/user-event';
 import Settings from '../SettingsPage/Settings';
 
 describe('Settings Page', () => {
   // shared setup for all tests
-  const setupTest = () => {
+  const setupTest = async () => {
     const user = userEvent.setup();
     render(<Settings />);
+    await act(async () => {
+      await new Promise((resolve) => setTimeout(resolve, 0));
+    });
     return { user };
   };
 
   describe('Interaction Sanity', () => {
     describe('User Preferences Section', () => {
       test('YOLO model dropdown opens and shows options', async () => {
-        const { user } = setupTest();
+        const { user } = await setupTest();
 
         const dropdownTrigger = screen.getByRole('button', {
           name: /nano|small|medium/i,
@@ -28,7 +31,7 @@ describe('Settings Page', () => {
       });
 
       test('GPU Acceleration toggle changes state on click', async () => {
-        const { user } = setupTest();
+        const { user } = await setupTest();
 
         const gpuSwitch = screen.getByRole('switch');
         expect(gpuSwitch).toHaveAttribute('aria-checked', 'false');
@@ -49,7 +52,7 @@ describe('Settings Page', () => {
       test.each(buttonCases)(
         '$label button does not crash when clicked',
         async ({ name }) => {
-          const { user } = setupTest();
+          const { user } = await setupTest();
 
           const button = screen.getByRole('button', { name });
 
@@ -71,7 +74,7 @@ describe('Settings Page', () => {
       test.each(yoloSelectionCases)(
         'selecting $expectedText updates dropdown display',
         async ({ selectOption, expectedText }) => {
-          const { user } = setupTest();
+          const { user } = await setupTest();
 
           const dropdownTrigger = screen.getByRole('button', { name: /nano/i });
           expect(dropdownTrigger).toHaveTextContent('Nano');
@@ -88,7 +91,7 @@ describe('Settings Page', () => {
       );
 
       test('dropdown can be reopened after selection', async () => {
-        const { user } = setupTest();
+        const { user } = await setupTest();
 
         const dropdownTrigger = screen.getByRole('button', { name: /nano/i });
         await user.click(dropdownTrigger);
@@ -102,7 +105,7 @@ describe('Settings Page', () => {
 
     describe('GPU Acceleration Toggle', () => {
       test('toggle cycles through ON/OFF states', async () => {
-        const { user } = setupTest();
+        const { user } = await setupTest();
 
         const gpuSwitch = screen.getByRole('switch');
         expect(gpuSwitch).toHaveAttribute('aria-checked', 'false');

frontend/src/pages/__tests__/allPages.test.tsx

@@ -1,4 +1,4 @@
-import { render } from '@testing-library/react';
+import { render, act } from '@testing-library/react';
 import { AITagging } from '@/pages/AITagging/AITagging';
 import Album from '../Album/Album';
 import { Home } from '@/pages/Home/Home';
@@ -23,7 +23,7 @@ const pages = [
 
 describe('Page rendering tests', () => {
   pages.forEach(({ path, Component }) => {
-    test(`renders ${path} without crashing`, () => {
+    test(`renders ${path} without crashing`, async () => {
       render(
         <Provider store={store}>
           <ThemeProvider>
@@ -35,6 +35,9 @@ describe('Page rendering tests', () => {
           </ThemeProvider>
         </Provider>,
       );
+      await act(async () => {
+        await new Promise((resolve) => setTimeout(resolve, 0));
+      });
     });
   });
 });