Reschedule download tasks when metadata is not ready

tubesync/sync/tasks.py

@@ -422,6 +422,8 @@ def download_media_thumbnail(media_id, url):
     except Media.DoesNotExist:
         # Task triggered but the media no longer exists, do nothing
         return
+    if not media.has_metadata:
+        raise DownloadFailedException('Metadata is not yet available.')
     if media.skip:
         # Media was toggled to be skipped after the task was scheduled
         log.warn(f'Download task triggered for media: {media} (UUID: {media.pk}) but '
@@ -459,6 +461,8 @@ def download_media(media_id):
     except Media.DoesNotExist:
         # Task triggered but the media no longer exists, do nothing
         return
+    if not media.has_metadata:
+        raise DownloadFailedException('Metadata is not yet available.')
     if media.skip:
         # Media was toggled to be skipped after the task was scheduled
         log.warn(f'Download task triggered for media: {media} (UUID: {media.pk}) but '