bug#61308: 28.2; icomplete --- Error in post-command-hook: wrong-type-argument

[Juri Linkov <juri@linkov.net>]

>   (progn
>     (with-eval-after-load 'icomplete
>       (customize-set-variable 'enable-recursive-minibuffers t)
>       (customize-set-variable 'help-window-select t)
>       (customize-set-variable 'icomplete-show-matches-on-no-input t))
>     (icomplete-mode))
>
> 2. C-x C-f
> 3. C-h v
> 4. Then RET (to select any candidate).
>
> Results in:
>
>   - The window displaying the *Help* buffer is selected, but an error[1]
>     is raised and I am left with the default Emacs completion system
>     when I return to the minibuffer.
>
> [1]  "Error in post-command-hook (icomplete-post-command-hook): (wrong-type-argument number-or-marker-p nil)"

Interesting bug report.  I guess we need to double-check
if we are still in the right buffer after help-window-select
selects another window and thus confuses icomplete-mode:

diff --git a/lisp/icomplete.el b/lisp/icomplete.el
index 014f38b2024..97457832e2c 100644
--- a/lisp/icomplete.el
+++ b/lisp/icomplete.el
@@ -686,6 +686,8 @@ icomplete-exhibit
 Should be run via minibuffer `post-command-hook'.
 See `icomplete-mode' and `minibuffer-setup-hook'."
   (when (and icomplete-mode
+             ;; Check if still in the right buffer (bug#61308)
+             (or (window-minibuffer-p) completion-in-region--data)
              (icomplete-simple-completing-p)) ;Shouldn't be necessary.
     (let ((saved-point (point)))
       (save-excursion