Fix limiting copying playlists

main.py

@@ -169,12 +169,12 @@ def copy_playlist_items(yt_api,
                         delete_from_src: bool = False,
                         limit: int = -1,
                         dry_run: bool = False):
-    if limit < 0:
-        limit = len(src_playlist)
-
     src_videos = list_playlist(yt_api, src_playlist)
     dst_videos = list_playlist(yt_api, dst_playlist)
 
+    if limit < 0:
+        limit = len(src_videos)
+
     dst_video_map = {video['snippet']['resourceId']['videoId']: video['id']
                      for video in dst_videos}