lei+net_reader: show NNTP message in more failures

Showing absolutely nothing when hitting a server requiring
authentication is a very bad user experience.  While we're
at it, use Net::Cmd->message in more places where we experience
failure, too.

1 files changed, 5 insertions, 1 deletions

diff --git a/lib/PublicInbox/LeiLsMailSource.pm b/lib/PublicInbox/LeiLsMailSource.pm
index 4b427b26..ab6c1e60 100644
--- a/lib/PublicInbox/LeiLsMailSource.pm
+++ b/lib/PublicInbox/LeiLsMailSource.pm
@@ -42,7 +42,11 @@ sub input_path_url { # overrides LeiInput version
                 my $uri = PublicInbox::URInntps->new($url);
                 my $nn = $lei->{net}->nn_get($uri) or
                         return $lei->err("E: $uri");
-                my $l = $nn->newsgroups($uri->group); # name => description
+                # $l = name => description
+                my $l = $nn->newsgroups($uri->group) // return $lei->err(<<EOM);
+E: $uri LIST NEWSGROUPS: ${\($lei->{net}->ndump($nn->message))}
+E: login may be required, try adding `-c nntp.debug' to your command
+EOM
                 my $sec = $lei->{net}->can('uri_section')->($uri);
                 if ($json) {
                         my $all = $nn->list;