Subject: bug#56865: M-x find-dired fails with "Wrong type: processp, nil"

From: Lars Ingebrigtsen <[email-masked]>
Date: Tue, 02 Aug 2022 12:34:58 +0200

Paul Pogonyshev <[email-masked]> writes:

> Tested also with `emacs -Q', so this is not a problem of my configuration.
>
> 1. Open (a slow) remote connection, with TRAMP
> 2. Run M-x find-dired RET, arguments not important
> 3. Internal error "Wrong type: processp, nil" appears
>
> Debugging suggests that it happens in `find-dired-with-command' when calling
> `set-process-filter'. Apparently the asynchronously started shell command started ~
> 30 lines above counts as having finished (?) by then.

The proper fix here would be to have a way to specify the
filter/sentinel in `shell-command', since that's the only way to really
guarantee that we'll be getting the output here.

But some testing seems to indicate that just moving the settings up
until right after the `shell-command' makes things work, so I've now
made that trivial fix in Emacs 29.  Does this fix this issue for you,
too?