Disable unavailable subreddits after Reddit 404

src/reddit/api.ts

@@ -24,6 +24,14 @@ export class RedditAccessDeniedError extends Error {
   }
 }
 
+/** Reddit confirms the community listing is gone and must no longer be polled. */
+export class RedditSubredditUnavailableError extends Error {
+  constructor(public readonly subreddit: string) {
+    super(`Reddit reports that r/${subreddit} is unavailable (HTTP 404)`);
+    this.name = 'RedditSubredditUnavailableError';
+  }
+}
+
 function getRateLimitDelayMs(headers: unknown): number {
   if (!headers || typeof headers !== 'object') return 60_000;
 
@@ -198,8 +206,7 @@ export class RedditApiClient {
     } catch (error) {
       if (axios.isAxiosError(error)) {
         if (error.response?.status === 404) {
-          this.logger.warn(`Subreddit r/${subreddit} not found`);
-          return [];
+          throw new RedditSubredditUnavailableError(subreddit);
         }
         if (error.response?.status === 403) {
           this.consecutiveListing403s += 1;