Merge pull request #3436 from feitianbubu/fix/email-identity-error-shadowing

fix(auth): stop swallowing email auth identity create error via shadowed err

backend/internal/service/auth_service.go

@@ -1042,7 +1042,7 @@ func (s *AuthService) ensureEmailAuthIdentity(ctx context.Context, user *User, s
 	}
 
 	if !existed {
-		if err := client.AuthIdentity.Create().
+		if err = client.AuthIdentity.Create().
 			SetUserID(user.ID).
 			SetProviderType("email").
 			SetProviderKey("email").