feat(auth): enhance error handling for sign-up and existing user checks (#14953)

Refactored error handling in `useSignUpInNewWorkspace` and `useSignInUp`
hooks to provide user-friendly messages. Added validation for existing
users during sign-up, updating server-side logic to throw specific
exceptions (`USER_ALREADY_EXIST`).

Fix
https://twenty-v7.sentry.io/issues/6686753138/events/latest/?environment=prod&project=4507072499810304&query=is%3Aunresolved%20issue.priority%3A%5Bhigh%2C%20medium%5D%20QueryFailedError&referrer=latest-event&sort=date

---------

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

packages/twenty-front/src/modules/auth/sign-in-up/hooks/useSignUpInNewWorkspace.ts

@@ -1,32 +1,38 @@
 import { useRedirectToWorkspaceDomain } from '@/domain-manager/hooks/useRedirectToWorkspaceDomain';
 import { useSnackBar } from '@/ui/feedback/snack-bar-manager/hooks/useSnackBar';
-import { type ApolloError } from '@apollo/client';
+import { ApolloError } from '@apollo/client';
 import { AppPath } from 'twenty-shared/types';
 import { useSignUpInNewWorkspaceMutation } from '~/generated-metadata/graphql';
 import { getWorkspaceUrl } from '~/utils/getWorkspaceUrl';
+import { assertIsDefinedOrThrow } from 'twenty-shared/utils';
+import { useLingui } from '@lingui/react/macro';
 
 export const useSignUpInNewWorkspace = () => {
   const { redirectToWorkspaceDomain } = useRedirectToWorkspaceDomain();
   const { enqueueErrorSnackBar } = useSnackBar();
+  const { t } = useLingui();
 
   const [signUpInNewWorkspaceMutation] = useSignUpInNewWorkspaceMutation();
 
   const createWorkspace = async ({ newTab } = { newTab: true }) => {
-    await signUpInNewWorkspaceMutation({
-      onCompleted: async (data) => {
-        return await redirectToWorkspaceDomain(
-          getWorkspaceUrl(data.signUpInNewWorkspace.workspace.workspaceUrls),
-          AppPath.Verify,
-          {
-            loginToken: data.signUpInNewWorkspace.loginToken.token,
-          },
-          newTab ? '_blank' : '_self',
-        );
-      },
-      onError: (error: ApolloError) => {
-        enqueueErrorSnackBar({ apolloError: error });
-      },
-    });
+    try {
+      const { data } = await signUpInNewWorkspaceMutation();
+      assertIsDefinedOrThrow(data?.signUpInNewWorkspace);
+      return await redirectToWorkspaceDomain(
+        getWorkspaceUrl(data.signUpInNewWorkspace.workspace.workspaceUrls),
+        AppPath.Verify,
+        {
+          loginToken: data.signUpInNewWorkspace.loginToken.token,
+        },
+        newTab ? '_blank' : '_self',
+      );
+    } catch (error) {
+      enqueueErrorSnackBar({
+        ...(error instanceof ApolloError
+          ? { apolloError: error }
+          : { message: t`Workspace creation failed` }),
+      });
+    }
   };
 
   return {