Description

Pressing Enter/Shift-Enter sends empty messages when input is empty, despite the "Send" button being disabled.

Reproduce

On v3-dev branch of Jupyter AI, press Enter/Shift-Enter repeatedly while the input is empty.

Expected behavior

• Enter/Shift-Enter should not send a message when the input is empty.
• When Enter/Shift-Enter is pressed:
  • Determine the message is all whitespace via regex, and if so, clear the input & do nothing else.
  • Otherwise, send the message.
  • The send button should be enabled/disabled according to this state. There should not be 2 separate state vars that control whether the send button is enabled & control whether the input should be sent.