It was possible on web to create a new sidebar with an empty (or including only
whitespaces) message.
The behavior now is that hitting enter in an empty textarea will create a newline (that
will be trimmed when the message is sent), similarly to other chatting apps.
Linear issue:
https://linear.app/comm/issue/ENG-1437/sending-empty-message-on-web-is-possible-for-pending-chat-and-creates