Fix isGroup in getDialogs

gramjs/tl/custom/dialog.ts

@@ -60,7 +60,7 @@ export class Dialog {
 
         this.isUser = this.entity instanceof Api.User;
         this.isGroup = !!(
-            (this.entity instanceof Api.Chat &&
+            (this.entity instanceof Api.Chat ||
                 this.entity instanceof Api.ChatForbidden) ||
             (this.entity instanceof Api.Channel && this.entity.megagroup)
         );