bug#72176: 30.0.60; icomplete-vertical-mode failed to work with Error

[Eason Huang <aqua0210@foxmail.com>]

Hello Emacs devel,

I tried to use icomplete-vertical-mode, but it doesn't works with
Emacs 30.0.60 and Emacs 31.0.50.

when trying `C-x C-f ~/` and input the first character of the names of
folders under home directory, will get bellow error:
```
Error in post-command-hook (icomplete-post-command-hook): (wrong-type-argument number-or-marker-p nil)
```

steps to reproduce:

1. start Emacs with `emacs -Q`
2. `M-x icomplete-vertical-mode` enable icomplete-vertical-mode
3. try to open some file under the directory under Home directory
   such as: `C-x C-f ~/` and then input the name a directory,
   here I will input `t` charactor, because I have the tmp folder.

4. Now you will get the error:

```
Error in post-command-hook (icomplete-post-command-hook): (wrong-type-argument number-or-marker-p nil)
```

 

In GNU Emacs 30.0.60 (build 1, x86_64-apple-darwin23.5.0, NS
 appkit-2487.60 Version 14.5 (Build 23F79), git sha1 5916b172bdc)
 of 2024-07-18 built on macbook
Windowing system distributor 'Apple', version 10.3.2487
System Description:  macOS 14.5

Configured using:
 'configure --without-native-compilation --without-dbus
 'CPPFLAGS=-I/opt/local/include
 -isysroot/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk'
 'LDFLAGS=-L/opt/local/lib -Wl,-headerpad_max_install_names -Wl,-rpath
 /opt/local/lib/gcc13
 -Wl,-syslibroot,/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk
 -arch x86_64''

Configured features:
ACL GIF GLIB GMP GNUTLS JPEG LCMS2 LIBXML2 MODULES NOTIFY KQUEUE NS
PDUMPER PNG RSVG SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER
WEBP XIM ZLIB

Important settings:
  value of $LANG: zh_CN.UTF-8
  locale-coding-system: utf-8-unix

Major mode: ELisp/l

Minor modes in effect:
  icomplete-vertical-mode: t
  icomplete-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  minibuffer-regexp-mode: t
  line-number-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny rfc822
mml mml-sec password-cache epa derived epg rfc6068 epg-config gnus-util
text-property-search mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils vc-git diff-mode track-changes easy-mmode
vc-dispatcher time-date subr-x dired-aux dired dired-loaddefs cus-start
cus-load icomplete cl-loaddefs cl-lib china-util rmc iso-transl tooltip
cconv eldoc paren electric uniquify ediff-hook vc-hooks lisp-float-type
elisp-mode mwheel term/ns-win ns-win ucs-normalize mule-util
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode lisp-mode prog-mode register
page tab-bar menu-bar rfn-eshadow isearch easymenu timer select
scroll-bar mouse jit-lock font-lock syntax font-core term/tty-colors
frame minibuffer nadvice seq simple cl-generic indonesian philippine
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads kqueue cocoa ns lcms2 multi-tty make-network-process emacs)

Memory information:
((conses 16 61505 15630) (symbols 48 7204 0) (strings 32 17696 2392)
 (string-bytes 1 421152) (vectors 16 11559)
 (vector-slots 8 187120 13794) (floats 8 26 263)
 (intervals 56 1455 20) (buffers 992 14))

-- 
Eason Huang