Add available function to check if episode streams are available

episode.go

@@ -112,6 +112,8 @@ func EpisodeFromID(crunchy *Crunchyroll, id string) (*Episode, error) {
 // Every episode in a season (should) have the same audio locale,
 // so if you want to get the audio locale of a season, just call
 // this method on the first episode of the season.
+// Will fail if no streams are available, thus use Available to
+// prevent any misleading errors.
 func (e *Episode) AudioLocale() (LOCALE, error) {
 	streams, err := e.Streams()
 	if err != nil {
@@ -120,6 +122,11 @@ func (e *Episode) AudioLocale() (LOCALE, error) {
 	return streams[0].AudioLocale, nil
 }
 
+// Available returns if downloadable streams for this episodes are available.
+func (e *Episode) Available() bool {
+	return e.crunchy.Config.Premium || !e.IsPremiumOnly
+}
+
 // GetFormat returns the format which matches the given resolution and subtitle locale.
 func (e *Episode) GetFormat(resolution string, subtitle LOCALE, hardsub bool) (*Format, error) {
 	streams, err := e.Streams()

url.go

@@ -49,6 +49,11 @@ func (c *Crunchyroll) ExtractEpisodesFromUrl(url string, audio ...LOCALE) ([]*Ep
 		}
 
 		for _, episode := range episodes {
+			// if no episode streams are available, calling episode.AudioLocale
+			// will result in an unwanted error
+			if !episode.Available() {
+				continue
+			}
 			locale, err := episode.AudioLocale()
 			if err != nil {
 				return nil, err

utils/sort.go

@@ -52,6 +52,9 @@ func SortEpisodesByAudio(episodes []*crunchyroll.Episode) (map[crunchyroll.LOCAL
 	var wg sync.WaitGroup
 	var lock sync.Mutex
 	for _, episode := range episodes {
+		if !episode.Available() {
+			continue
+		}
 		episode := episode
 		wg.Add(1)
 		go func() {