master e275dd2894: Avoid error when forwarding messages from Rmail

[Eli Zaretskii]

branch: master
commit e275dd289437547414b22cda3227305fb6a85854
Author: Nicolas Graner <nicolas@graner.name>
Commit: Eli Zaretskii <eliz@gnu.org>

    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)
---
 lisp/gnus/message.el | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lisp/gnus/message.el b/lisp/gnus/message.el
index 24cba97718..3bbd68bdcd 100644
--- 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))))