Sending an empty message results in a silent server error

[krassowski]

Description

Sending empty message:

• (a) is possible despite the send button being greyed out
• (b) results in an error on the server side:

Task exception was never retrieved
future: <Task finished name='Task-21794' coro=<RootChatHandler._route() done, defined at jupyter-ai/packages/jupyter-ai/jupyter_ai/handlers.py:220> exception=IndexError('list index out of range')>
Traceback (most recent call last):
  File "jupyter-ai/packages/jupyter-ai/jupyter_ai/handlers.py", line 224, in _route
    maybe_command = message.body.split(None, 1)[0]
IndexError: list index out of range

Reproduce

Go to chat and press Enter

Expected behavior

• It is not possible to send empty message
• There is not server-side error

Context

• JupyterLab version: 4.2.0
• Extension 4.16.0

[dlqqq]

@krassowski I just noticed this as well! I suspect that this was caused by some regression in the UI.