Only prompt box closes when using :bd on :ChatGPT

## What I want to do
Get out of the ChatGPT chat by closing the buffer using :bd

## What happens
when I am typing, only the prompt is closed, and the chat window remains open

## What I expected
For the entire window to close when using :bd

## How to replicate
1. Use the `:ChatGPT` command
2. type a prompt (or not, occurs either way)
3. press in INSERT mode
4. enter normal mode
5. press
6. use the :bd command

It appears that this is due to pressing in INSERT mode beforehand.

Reproduce the issue with the listed :ChatGPT, INSERT-mode , , and :bd steps, then trace the ChatGPT buffer and window handling. The fix is complete when :bd closes the entire ChatGPT window, including after a prompt has been entered.

Written by the indexing model from the issue text.