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/tests/unit/test_messages.py

@@ -195,26 +195,27 @@ async def test_aupdate_multiple_messages(created_messages):
 
 
 @pytest.mark.usefixtures("client")
-async def test_aupdate_nonexistent_message():
+async def test_aupdate_nonexistent_message_generates_a_new_message():
     # Create a message with a non-existent UUID
+    nonexistent_uuid = uuid4()
     message = MessageRead(
-        id=uuid4(),  # Generate a random UUID that won't exist in the database
+        id=nonexistent_uuid,  # Generate a random UUID that won't exist in the database
         text="Test message",
         sender="User",
         sender_name="User",
         session_id="session_id",
         flow_id=uuid4(),
     )
-
-    updated = await aupdate_messages(message)
-    assert len(updated) == 0
+    with pytest.raises(ValueError, match=f"Message with id {nonexistent_uuid} not found"):
+        await aupdate_messages(message)
 
 
 @pytest.mark.usefixtures("client")
 async def test_aupdate_mixed_messages(created_messages):
     # Create a mix of existing and non-existing messages
+    nonexistent_uuid = uuid4()
     nonexistent_message = MessageRead(
-        id=uuid4(),  # Generate a random UUID that won't exist in the database
+        id=nonexistent_uuid,  # Generate a random UUID that won't exist in the database
         text="Test message",
         sender="User",
         sender_name="User",
@@ -225,7 +226,11 @@ async def test_aupdate_mixed_messages(created_messages):
     messages_to_update = created_messages[:1] + [nonexistent_message]
     created_messages[0].text = "Updated existing message"
 
-    updated = await aupdate_messages(messages_to_update)
+    with pytest.raises(ValueError, match=f"Message with id {nonexistent_uuid} not found"):
+        await aupdate_messages(messages_to_update)
+
+    # Update just the existing message
+    updated = await aupdate_messages(created_messages[:1])
 
     assert len(updated) == 1
     assert updated[0].text == "Updated existing message"