t/nntp.t: attempt to track source of undefined vars

Occasionally, t/nntp.t spews undefined variable warnings under
`make check-run'.  While the test doesn't fail, it's annoying
to see them and it could be a source of deeper problems.

1 files changed, 5 insertions, 2 deletions

diff --git a/t/nntp.t b/t/nntp.t
index 0d3384d7..42a4ea97 100644
--- a/t/nntp.t
+++ b/t/nntp.t
@@ -3,14 +3,17 @@
 use v5.12;
 use PublicInbox::TestCommon;
 use PublicInbox::Eml;
-require_mods(qw(DBD::SQLite Data::Dumper));
+require_mods(qw(DBD::SQLite));
 use_ok 'PublicInbox::NNTP';
 use PublicInbox::Config;
 use POSIX qw(strftime);
+use Data::Dumper;
 
 {
         my $quote_str = sub {
-                my (undef, $s) = split(/ = /, Data::Dumper::Dumper($_[0]), 2);
+                my ($orig) = @_;
+                my (undef, $s) = split(/ = /, Dumper($orig), 2);
+                $s // diag explain(['$s undefined, $orig = ', $orig]);
                 $s =~ s/;\n//;
                 $s;
         };