Make exception handling for cover art fetching more tolerant

Use the parent class WebServiceError to cover all errors related to MusicBrainz API requests (ResponseError, NetworkError and AuthenticationError)

Signed-off-by: Loïc CORBASSON <loic.devel@corbasson.fr>

Author: lcorbasson

whipper/common/program.py

@@ -529,7 +529,7 @@ def getCoverArt(path, release_id):
         logger.debug('fetching cover art for release: %r', release_id)
         try:
             data = musicbrainzngs.get_image_front(release_id, 500)
-        except musicbrainzngs.ResponseError as e:
+        except musicbrainzngs.WebServiceError as e:
             logger.error('error fetching cover art: %r', e)
             return