feat: add support for topic/auto-generated channels and fix minor parsing errors (#233)

* dev: add support for topic channels

* dev(parser): do not try to parse empty nodes

* dev: add support for auto-generated game channels

src/parser/classes/TopicChannelDetails.ts

@@ -0,0 +1,27 @@
+import Parser from '..';
+import { YTNode } from '../helpers';
+
+import Text from './misc/Text';
+import Thumbnail from './misc/Thumbnail';
+import NavigationEndpoint from './NavigationEndpoint';
+import SubscribeButton from './SubscribeButton';
+
+export default class TopicChannelDetails extends YTNode {
+  static type = 'TopicChannelDetails';
+
+  title: Text;
+  avatar: Thumbnail[];
+  subtitle: Text;
+  subscribe_button: SubscribeButton | null;
+  endpoint: NavigationEndpoint;
+
+  constructor (data: any) {
+    super();
+
+    this.title = new Text(data.title);
+    this.avatar = Thumbnail.fromResponse(data.thumbnail);
+    this.subtitle = new Text(data.title);
+    this.subscribe_button = Parser.parseItem<SubscribeButton>(data.subscribeButton, SubscribeButton);
+    this.endpoint = new NavigationEndpoint(data.navigationEndpoint);
+  }
+}