content_digest_dbg: handle empty inputs

It's possible that we hit messages or attachments with empty
bodies, so avoid doing a regexp match on an uninitialized variable.

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/PublicInbox/ContentDigestDbg.pm b/lib/PublicInbox/ContentDigestDbg.pm
index 31d0f707..853624f1 100644
--- a/lib/PublicInbox/ContentDigestDbg.pm
+++ b/lib/PublicInbox/ContentDigestDbg.pm
@@ -11,7 +11,7 @@ sub new { bless [ PublicInbox::SHA->new(256), $_[1] ], __PACKAGE__ }
 sub add {
         $_[0]->[0]->add($_[1]);
         my @dbg = split(/^/sm, $_[1]);
-        if ($dbg[0] =~ /\A(To|Cc)\0/) { # fold excessively long lines
+        if (@dbg && $dbg[0] =~ /\A(To|Cc)\0/) { # fold excessively long lines
                 @dbg = map { split(/,/s, $_) } @dbg;
         }
         print { $_[0]->[1] } Dumper(\@dbg) or die "print $!";