fix getting tracks with fallbacks

index.js

@@ -173,6 +173,11 @@ async function track(id, format, access_token, tagging) {
 }
 
 async function track_url(json, format) {
+    // needed if track has fallback, like https://www.deezer.com/track/1398759152
+    if (json.alternative) {
+        json = json.alternative
+    }
+
     const id = json.id
     const md5_origin = json.md5_origin
     const media_version = json.media_version