bug#71337: 30.0.50; `electric-pair-mode' and custom keybinding

[Arash Esbati]

Hi all,

I have a custom keybinding "s-ß" with my German keyboard, but the issue
I'm facing is also reproducible like this:

• emacs -Q
• In scratch, eval:

  (progn
    (setq debug-on-error t)
    (electric-pair-mode  1)
    (keymap-global-set "s-#" (lambda (arg)
                               "Insert ARG backslash(es)."
                               (interactive "*p")
                               (self-insert-command arg ?\\))))

• Now hit "s-#" and the debugger says (linebreaks added manually):

Debugger entered--Lisp error: (wrong-type-argument characterp 8388643)
  #f(compiled-function () #<bytecode -0x15954a2c5d74b890>)()
  electric-pair--with-syntax-1(nil #f(compiled-function () #<bytecode 
-0x15954a2c5d74b890>))
  electric-pair-syntax-info(8388643)
  electric-pair-post-self-insert-function()
  self-insert-command(1 92)
  #f(lambda (arg) [t] "Insert ARG backslash(es)." (interactive "*p")
   (self-insert-command arg 92))(1)
  funcall-interactively(#f(lambda (arg) [t] "Insert ARG backslash(es)."
   (interactive "*p") (self-insert-command arg 92)) 1)
  command-execute(#f(lambda (arg) [t] "Insert ARG backslash(es)."
   (interactive "*p") (self-insert-command arg 92)))

Running the exercise with (electric-pair-mode -1) doesn't throw an
error.

Best, Arash

In GNU Emacs 30.0.50 (build 1, aarch64-apple-darwin23.5.0, NS
 appkit-2487.60 Version 14.5 (Build 23F79)) of 2024-05-28 built on
 MacMutant.local
Repository revision: 066e9b598858cc4c0b666b12242f07a7fdf3e073
Repository branch: master
Windowing system distributor 'Apple', version 10.3.2487
System Description:  macOS 14.5

Configured using:
 'configure --with-ns --without-pop --without-mailutils --with-threads
 --with-modules --with-native-compilation --without-compress-install
 'CFLAGS=-O2 -g0 -pipe'
 'CPPFLAGS=-I/opt/homebrew/Cellar/gcc/14.1.0/include
 -I/opt/homebrew/Cellar/libgccjit/14.1.0/include
 -I/opt/homebrew/Cellar/gmp/6.3.0/include'
 'LDFLAGS=-L/opt/homebrew/Cellar/gcc/14.1.0/lib/gcc/current
 -L/opt/homebrew/Cellar/gmp/6.3.0/lib''

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