fix: Improve error handling in aupdate_messages function to prevent empty message error (#5655)

* refactor: Improve error handling in aupdate_messages function

* Update src/backend/base/langflow/memory.py

Co-authored-by: Gabriel Luiz Freitas Almeida <gabriel@langflow.org>

* fix(tests): updating a non-existing message adds a new message now

- Updated the test name from `test_aupdate_nonexistent_message` to `test_aupdate_nonexistent_message_generates_a_new_message` for better clarity.
- Modified the assertion to expect that a new message is generated when attempting to update a nonexistent message, changing the expected length of the updated messages from 0 to 1.

* [autofix.ci] apply automated fixes

* fix(tests): update message handling in tests for non-existent messages

- Refactored tests to ensure that attempting to update a non-existent message raises a ValueError instead of creating a new message.
- Updated test names and assertions for clarity and accuracy, ensuring they reflect the expected behavior when handling messages that do not exist in the database.

---------

Co-authored-by: Gabriel Luiz Freitas Almeida <gabriel@langflow.org>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

src/backend/base/langflow/memory.py

@@ -144,7 +144,9 @@ async def aupdate_messages(messages: Message | list[Message]) -> list[Message]:
                 await session.refresh(msg)
                 updated_messages.append(msg)
             else:
-                logger.warning(f"Message with id {message.id} not found")
+                error_message = f"Message with id {message.id} not found"
+                logger.warning(error_message)
+                raise ValueError(error_message)
         return [MessageRead.model_validate(message, from_attributes=True) for message in updated_messages]
 
 
@@ -255,7 +257,12 @@ async def astore_message(
         msg = "All of session_id, sender, and sender_name must be provided."
         raise ValueError(msg)
     if hasattr(message, "id") and message.id:
-        return await aupdate_messages([message])
+        # if message has an id and exist in the database, update it
+        # if not raise an error and add the message to the database
+        try:
+            return await aupdate_messages([message])
+        except ValueError as e:
+            logger.error(e)
     if flow_id and not isinstance(flow_id, UUID):
         flow_id = UUID(flow_id)
     return await aadd_messages([message], flow_id=flow_id)