I think so.

• If there's something in the internal buffer in the end, we want to send it to the user in an additional message (that's why returning null here - that means, we're sending the current message and in the next cycle, we're handling logs).
• If there's nothing in the internal buffer, we just want to proceed to handle logs without sending anything.

Also, setting state to LOGS should be the last operation, just before the return.

No, it's ok. The state should be set to sending logs regardless of whether we send the last message with the internal buffer for compaction or we just proceed to handle the logs.