Transcripts: say why a show's own transcript was not found; read Podgrab fields whatever their capitals

tools/transcript-test.js

@@ -33,7 +33,8 @@ let bad = 0; const ok = (c, m) => { console.log((c ? 'PASS  ' : 'FAIL  ') + m);
   const feed = `<item><guid>g1</guid><podcast:transcript url="https://a/b.srt?x=1&amp;y=2" type="application/x-subrip"/></item><item><guid>g2</guid><enclosure url="https://f/2.mp3" length="1"/><podcast:transcript url="https://a/c.vtt" type="text/vtt"/></item>`;
   ok(tr.transcriptLinks(feed, 'g1', '')[0].url === 'https://a/b.srt?x=1&y=2', 'a transcript link is found by the episode guid (and & unescaped)');
   ok(tr.transcriptLinks(feed, 'nope', 'https://f/2.mp3')[0].type === 'text/vtt', 'or by the audio file address');
-  ok(tr.transcriptLinks(feed, 'zzz', '').length === 0, 'another episode has none');
+  ok(tr.transcriptLinks(feed, 'zzz', '') === null, 'an episode that is not in the feed is told apart from one with no transcript');
+  ok(tr.transcriptLinks('<item><guid>q</guid></item>', 'q', '').length === 0, 'an episode with no transcript tag gives an empty list');
 
   for (const u of ['http://127.0.0.1:1/x', 'http://localhost/x', 'http://192.168.1.5/x', 'http://10.0.0.2/x', 'ftp://example.com/x', 'http://[::1]/x']) {
     let e = null; try { await tr.getText(u); } catch (x) { e = x; } ok(e && /not allowed/.test(e.message), 'refuses ' + u);