Subject: bug#63837: 29.0.91; delete-forward-char error with composed text

From: Thiago Melo <[email-masked]>
Date: Fri, 2 Jun 2023 10:42:29 +0000

* How to reproduce:

0. Start emacs with `emacs -Q'
1. Create some text composition, e.g. eval: `(insert (compose-chars ?+))'
2. Move cursor to before composed character
3. `M-x delete-forward-char' or press <delete> key

* Backtrace:

Debugger entered--Lisp error: (wrong-type-argument sequencep t)
  lgstring-glyph-boundary(t 1 2)
  delete-forward-char(1 nil)
  funcall-interactively(delete-forward-char 1 nil)
  call-interactively(delete-forward-char nil nil)
  command-execute(delete-forward-char)