An empty dialog with no messages appeared in WhatsApp

Empty messages can appear when the program:

1. Takes an account and starts sending one or several messages.
2. Doesn't wait for sending to finish and marks the status as ERROR.
3. Switches to the next account to resend to the same numbers (often successfully).
4. Comes back to the first account and removes the old unsent messages from the database to avoid duplicates. That's how an empty dialog appears.