[docs] Improvements

[yt-dlp.git] / yt_dlp / YoutubeDL.py

diff --git a/yt_dlp/YoutubeDL.py b/yt_dlp/YoutubeDL.py
index f38697365a21786611747e98ef15976bc4892d0b..2a4c8c883ad52cf72931b27d06b6857d45fb74de 100644 (file)
--- a/yt_dlp/YoutubeDL.py
+++ b/yt_dlp/YoutubeDL.py
@@ -769,6 +769,7 @@ def add_default_info_extractors(self):
 
     def add_post_processor(self, pp, when='post_process'):
         """Add a PostProcessor object to the end of the chain."""
+        assert when in POSTPROCESS_WHEN, f'Invalid when={when}'
         self._pps[when].append(pp)
         pp.set_downloader(self)