Trivial unrmail fix for empty input files.

* lisp/mail/unrmail.el (unrmail): Give an explicit error if the input
file has no messages.

Fixes: debbugs:10377

1 files changed, 2 insertions, 1 deletions

diff --git a/lisp/mail/unrmail.el b/lisp/mail/unrmail.el
index 178b64f1191..929f97746b0 100644
--- a/lisp/mail/unrmail.el
+++ b/lisp/mail/unrmail.el
@@ -66,7 +66,8 @@ For example, invoke `emacs -batch -f batch-unrmail RMAIL'."
           from to)
       (goto-char (point-min))
       (search-forward "\n\^_" nil t)    ; Skip BABYL header.
-      (setq from (point))
+      (if (= (setq from (point)) (point-max))
+          (error "The input file contains no messages"))
       (goto-char (point-max))
       (search-backward "\n\^_" from 'mv)
       (setq to (point))