Handle error if no "to" address is found

Previously `substring` would give an error if the "to" address from
"git config --list" was empty.  This meant that no message would be
created.  This patch fixes this and instead returns an empty string if
to "to" address was found.

Signed-off-by: Xinglu Chen <public@yoctocell.xyz>

1 files changed, 5 insertions, 3 deletions

diff --git a/git-email.el b/git-email.el
index e79f486..3837d8b 100644
--- a/git-email.el
+++ b/git-email.el
@@ -273,9 +273,11 @@ If the header is not found, return an empty string."
 
 This runs \“git config --list\" in the current directory
 so might not always work."
-  (substring
-   (shell-command-to-string "git config --list | grep sendemail.to")
-   13 -1))                              ; Remove newline
+  (let* ((to (shell-command-to-string  "git config --list | grep sendemail.to"))
+         (address (if (string= "" to)
+                      ""
+                    (substring to 13 -1)))) ; Remove newline
+    address))
 
 (defun git-email--compose-email (patch-file)
   "Given a PATCH-FILE, compose an email.