Deals with https://github.com/zed-industries/community/issues/1898

Restores original close behavior from
https://github.com/zed-industries/zed/pull/2832/files#diff-89af0b4072205c53b518aa977d6be48997e1a51fa4dbf06c7ddd1fec99fc510eL444
(load diff for the last file, zed.rs)

and adds a better name for the variable.

Release Notes:

- Fixes `cmd-q` not working