UNAUTHORIZED gmail error (#12262)

# Gmail OAuth authentication flow issues

### TLDR
This error is not an error and therefore should be treated as a simple
redirect with a snackbar.

### More details
Fixing incomplete OAuth token exchange processes and improving error
handling for empty Gmail inboxes.
The changes include modifications to OAuth guards, to ensure that if a
user clicks "cancel" instead of completing the authentication workflow
if fails

## Before:
Redirection from `/settings/accounts` to `app.twenty.com` with an
`UNAUTHORIZED` error

## After :
<img width="948" alt="Screenshot 2025-05-26 at 18 04 37"
src="https://github.com/user-attachments/assets/62c8721e-c2b3-4e3d-ad0b-e4059dfb7a98"
/>


Fixes https://github.com/twentyhq/twenty/issues/11895

---------

Co-authored-by: Charles Bochet <charles@twenty.com>

packages/twenty-front/src/modules/app/components/AppRouterProviders.tsx

@@ -8,6 +8,7 @@ import { ChromeExtensionSidecarProvider } from '@/chrome-extension-sidecar/compo
 import { ClientConfigProvider } from '@/client-config/components/ClientConfigProvider';
 import { ClientConfigProviderEffect } from '@/client-config/components/ClientConfigProviderEffect';
 import { MainContextStoreProvider } from '@/context-store/components/MainContextStoreProvider';
+import { ErrorMessageEffect } from '@/error-handler/components/ErrorMessageEffect';
 import { PromiseRejectionEffect } from '@/error-handler/components/PromiseRejectionEffect';
 import { ApolloMetadataClientProvider } from '@/object-metadata/components/ApolloMetadataClientProvider';
 import { ObjectMetadataItemsLoadEffect } from '@/object-metadata/components/ObjectMetadataItemsLoadEffect';
@@ -49,6 +50,7 @@ export const AppRouterProviders = () => {
                       <PrefetchDataProvider>
                         <UserThemeProviderEffect />
                         <SnackBarProvider>
+                          <ErrorMessageEffect />
                           <DialogManagerScope dialogManagerScopeId="dialog-manager">
                             <DialogManager>
                               <StrictMode>