Fix a crash when downloading a disabled pornhub video

bdfr/site_downloaders/pornhub.py

@@ -6,6 +6,7 @@ from typing import Optional
 
 from praw.models import Submission
 
+from bdfr.exceptions import SiteDownloaderError
 from bdfr.resource import Resource
 from bdfr.site_authenticator import SiteAuthenticator
 from bdfr.site_downloaders.youtube import Youtube
@@ -22,10 +23,15 @@ class PornHub(Youtube):
             'format': 'best',
             'nooverwrites': True,
         }
+        if video_attributes := super().get_video_attributes(self.post.url):
+            extension = video_attributes['ext']
+        else:
+            raise SiteDownloaderError()
+
         out = Resource(
             self.post,
             self.post.url,
             super()._download_video(ytdl_options),
-            super().get_video_attributes(self.post.url)['ext'],
+            extension,
         )
         return [out]