viewvcs: avoid uninitialized var on unusable filenames

This happens if somebody uses a bogus filename like `.' for the
`b=' parameter (e.g. GET `$REPO/$OID/?b=.').

1 files changed, 1 insertions, 1 deletions

diff --git a/lib/PublicInbox/ViewVCS.pm b/lib/PublicInbox/ViewVCS.pm
index de8600ee..eb757089 100644
--- a/lib/PublicInbox/ViewVCS.pm
+++ b/lib/PublicInbox/ViewVCS.pm
@@ -514,7 +514,7 @@ sub solve_result {
         return show_other($ctx, $res) if $type ne 'blob';
         my $fn = $di->{path_b} // $hints->{path_b};
         my $paths = $ctx->{-paths} //= do {
-                my $path = to_filename($fn // 'blob');
+                my $path = to_filename($fn // 'blob') // 'blob';
                 my $raw_more = qq[(<a\nhref="$path">raw</a>)];
                 my @def;