Fixed anidb refiner special episodes without offset (#2736)

bazarr/subtitles/refiners/anidb.py

@@ -91,11 +91,11 @@ class AniDBClient(object):
                 return None, None, None
 
             is_special_entry = True
+
             for special_entry in special_entries:
                 mapping_list = special_entry.findall(f".//mapping[@tvdbseason='{tvdb_series_season}']")
-                if len(mapping_list) > 0:
-                    anidb_id = int(special_entry.attrib.get('anidbid'))
-                    offset = int(mapping_list[0].attrib.get('offset', 0))
+                anidb_id = int(special_entry.attrib.get('anidbid'))
+                offset = int(mapping_list[0].attrib.get('offset', 0)) if len(mapping_list) > 0 else 0
 
         if not is_special_entry:
             # Sort the anime by offset in ascending order