If last-command-char is not a character, don't do the expand here.
;; the mail-mode-header-syntax-table.
(set-syntax-table mail-mode-header-syntax-table)
- (or (eq (char-syntax last-command-char) ?_)
+ (or (not (integerp last-command-char))
+ (eq (char-syntax last-command-char) ?_)
(let ((pre-abbrev-expand-hook nil)) ; That's us; don't loop.
;; Use this table so that abbrevs can have hyphens in them.
(set-syntax-table mail-abbrev-syntax-table)