fix(route/podcast): add fallback channel data (DIYgod#20099)

Author: TonyRL

lib/routes/apple/podcast.ts

@@ -92,15 +92,15 @@ async function handler(ctx) {
         };
     });
 
-    const channel = episodeReponse.data.find((d) => d.type === 'podcast-episodes').relationships.channel.data.find((d) => d.type === 'podcast-channels').attributes;
+    const channel = episodeReponse.data.find((d) => d.type === 'podcast-episodes').relationships.channel.data.find((d) => d.type === 'podcast-channels')?.attributes;
 
     return {
-        title: channel.name,
-        link: channel.url,
+        title: channel?.name ?? header.title,
+        link: channel?.url ?? header.contextAction.podcastOffer.storeUrl,
         itunes_author: header.contextAction.podcastOffer.author,
         item: episodes,
-        description: (header.description || channel.description.standard).replaceAll('\n', ' '),
-        image: (channel.logoArtwork || channel.subscriptionArtwork).url.replace(/\{w\}x\{h\}(?:\{c\}|bb)\.\{f\}/, '3000x3000bb.webp'),
+        description: (header.description || channel?.description.standard)?.replaceAll('\n', ' '),
+        image: ((channel?.logoArtwork || channel?.subscriptionArtwork)?.url || header.contextAction.podcastOffer.artwork.template).replace(/\{w\}x\{h\}(?:\{c\}|bb)\.\{f\}/, '3000x3000bb.webp'),
         itunes_category: header.metadata.find((d) => Object.hasOwn(d, 'category')).category?.title || header.metadata.find((d) => Object.hasOwn(d, 'category')).category,
     };
 }