fix: improve UUID handling in custom component variables (#5230)

* 🐛 (custom_component.py): fix user_id assignment to convert it to UUID type for consistency and correctness

* [autofix.ci] apply automated fixes

* 🐛 (custom_component.py): fix potential bug by checking if self.user_id is a string before converting it to UUID

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

src/backend/base/langflow/custom/custom_component/custom_component.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import asyncio
+import uuid
 from collections.abc import Callable, Sequence
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, ClassVar
@@ -439,7 +440,8 @@ class CustomComponent(BaseComponent):
         variable_service = get_variable_service()  # Get service instance
         # Retrieve and decrypt the variable by name for the current user
         async with async_session_scope() as session:
-            user_id = self.user_id or ""
+            if isinstance(self.user_id, str):
+                user_id = uuid.UUID(self.user_id)
             return await variable_service.get_variable(user_id=user_id, name=name, field=field, session=session)
 
     async def list_key_names(self):