bug(youtube.dl): Fix crash on zero downloads #375

bdfr/site_downloaders/youtube.py

@@ -8,7 +8,7 @@ from typing import Optional
 import youtube_dl
 from praw.models import Submission
 
-from bdfr.exceptions import SiteDownloaderError
+from bdfr.exceptions import (NotADownloadableLinkError, SiteDownloaderError)
 from bdfr.resource import Resource
 from bdfr.site_authenticator import SiteAuthenticator
 from bdfr.site_downloaders.base_downloader import BaseDownloader
@@ -43,7 +43,12 @@ class Youtube(BaseDownloader):
             except youtube_dl.DownloadError as e:
                 raise SiteDownloaderError(f'Youtube download failed: {e}')
 
-            downloaded_file = list(download_path.iterdir())[0]
+            downloaded_file = None
+            downloaded_files = list(download_path.iterdir())
+            if len(downloaded_files) > 0:
+                downloaded_file = downloaded_files[0]
+            else:
+                raise NotADownloadableLinkError(f"No media exists in the URL {self.post.url}")
             extension = downloaded_file.suffix
             with open(downloaded_file, 'rb') as file:
                 content = file.read()