Revert "Revert "Give better errors in signing failures in Gnus""

This reverts commit 42141da5b0885b199636524c1e57f08ee1723aea.

This patch was reverted in error.  I misinterpreted an email saying that
it didn't work, but apparently it worked as it should.

2 files changed, 4 insertions, 0 deletions

diff --git a/lisp/gnus/mml1991.el b/lisp/gnus/mml1991.el
index 93b1b5049a8..b2056b2fd0d 100644
--- a/lisp/gnus/mml1991.el
+++ b/lisp/gnus/mml1991.el
@@ -275,6 +275,8 @@ Whether the passphrase is cached at all is controlled by
 	(mm-decode-content-transfer-encoding cte)))
     (let* ((pair (mml-secure-epg-sign 'OpenPGP 'clear))
 	   (signature (car pair)))
+      (unless (stringp signature)
+        (error "Signature failed"))
       (delete-region (point-min) (point-max))
       (insert
        (with-temp-buffer
diff --git a/lisp/gnus/mml2015.el b/lisp/gnus/mml2015.el
index 5980ddb38fe..403b5e1af6a 100644
--- a/lisp/gnus/mml2015.el
+++ b/lisp/gnus/mml2015.el
@@ -958,6 +958,8 @@ If set, it overrides the setting of `mml2015-sign-with-sender'."
     (let* ((pair (mml-secure-epg-sign 'OpenPGP t))
 	   (signature (car pair))
 	   (micalg (cdr pair)))
+      (unless (stringp signature)
+        (error "Signature failed"))
       (goto-char (point-min))
       (insert (format "Content-Type: multipart/signed; boundary=\"%s\";\n"
 		      boundary))