fix: properly handle comment replies

Turns out that when fixing thislooksfun#67 I accidentally broke comment replies. Now
they are working again.

Fixes thislooksfun#71.

src/reddit/comment/listing/listing.ts

@@ -1,3 +1,4 @@
+import type { Maybe } from "../../../helper/types";
 import type {
   Fetcher,
   ListingContext,
@@ -13,24 +14,31 @@ import { CommentPager } from "./pager";
 
 const debug = makeDebug("listing:comment");
 
+function makeFetcher(
+  after: RedditListing["after"],
+  context: ListingContext
+): Maybe<Fetcher<Comment>> {
+  if (after == undefined) return undefined;
+
+  if (after === "" && context.post) {
+    return new MoreComments({
+      children: [],
+      count: 0,
+      depth: 0,
+      id: "_",
+      name: "t1__",
+      // eslint-disable-next-line @typescript-eslint/naming-convention
+      parent_id: context.client.posts.namespace(context.post),
+    });
+  }
+
+  return new CommentPager(after);
+}
+
 /** @internal */
 export class CommentListing extends Listing<Comment> {
   constructor(l: RedditListing, context: ListingContext) {
-    let fetcher: Fetcher<Comment> | undefined;
-
-    if (context.post) {
-      fetcher = new MoreComments({
-        children: [],
-        count: 0,
-        depth: 0,
-        id: "_",
-        name: "t1__",
-        // eslint-disable-next-line @typescript-eslint/naming-convention
-        parent_id: context.client.posts.namespace(context.post),
-      });
-    } else if (l.after != undefined) {
-      fetcher = new CommentPager(l.after);
-    }
+    let fetcher: Maybe<Fetcher<Comment>>;
 
     const comments: Comment[] = [];
     for (const c of l.children) {
@@ -47,6 +55,8 @@ export class CommentListing extends Listing<Comment> {
       }
     }
 
+    fetcher ??= makeFetcher(l.after, context);
+
     super(context, comments, fetcher);
   }
 }