Avoid error when forwarding messages from Rmail

* lisp/gnus/message.el (message-mail): Verify that In-Reply-To has
a string value before matching it with a regexp.  (Bug#59007)

diff --git a/lisp/gnus/message.el b/lisp/gnus/message.el
index 24cba97718a0dd6e77c2b545fbf03ad0fe0dea5f..3bbd68bdcd7e9473c79da50158298bb3ae17b515 100644 (file)
--- a/lisp/gnus/message.el
+++ b/lisp/gnus/message.el
@@ -7034,6 +7034,7 @@ is a function used to switch to and display the mail buffer."
           ;; Firefox sends us In-Reply-To headers that are Message-IDs
           ;; without <> around them.  Fix that.
           (when (and (eq (car h) 'In-Reply-To)
+                     (stringp (cdr h))
                      ;; Looks like a Message-ID.
                      (string-match-p "\\`[^ @]+@[^ @]+\\'" (cdr h))
                      (not (string-match-p "\\`<.*>\\'" (cdr h))))