Ensure _type is present in info.json

Closes yt-dlp#2447

Author: pukkandan

yt_dlp/YoutubeDL.py

@@ -3211,6 +3211,7 @@ def sanitize_info(info_dict, remove_private_keys=False):
         if info_dict is None:
             return info_dict
         info_dict.setdefault('epoch', int(time.time()))
+        info_dict.setdefault('_type', 'video')
         remove_keys = {'__original_infodict'}  # Always remove this since this may contain a copy of the entire dict
         keep_keys = ['_type']  # Always keep this to facilitate load-info-json
         if remove_private_keys: