feat: implement account email mismatch error handling and improve user feedback in authentication flows

src/langbot/pkg/api/http/controller/groups/user.py

@@ -4,6 +4,7 @@ import asyncio
 import traceback
 
 from .. import group
+from .....entity.errors import account as account_errors
 
 
 @group.group_class('user', '/api/v1/user')
@@ -141,6 +142,8 @@ class UserRouterGroup(group.RouterGroup):
                         'user': user_obj.user,
                     }
                 )
+            except account_errors.AccountEmailMismatchError as e:
+                return self.fail(3, str(e))
             except ValueError as e:
                 traceback.print_exc()
                 return self.fail(1, str(e))

src/langbot/pkg/api/http/service/user.py

@@ -10,6 +10,7 @@ import asyncio
 from ....core import app
 from ....entity.persistence import user
 from ....utils import constants
+from ....entity.errors import account as account_errors
 
 
 class UserService:
@@ -174,9 +175,7 @@ class UserService:
             # Check if system is already initialized
             is_initialized = await self.is_initialized()
             if is_initialized:
-                raise ValueError(
-                    'This LangBot instance already has an account. Please use the existing account to login.'
-                )
+                raise account_errors.AccountEmailMismatchError()
 
             # Create new Space user (first time initialization)
             await self.ap.persistence_mgr.execute_async(