fixed decrypting tracks with fallback

index.js

@@ -184,6 +184,11 @@ async function track(id, format, access_token, tagging) {
         writer.write(id3.arrayBuffer)
     }
 
+    // needed if track has fallback, like https://www.deezer.com/track/11835714
+    if (json.alternative) {
+        id = json.alternative.id.toString()
+    }
+
     const bfKey = await bf_key(id)
     const length = Number(track.headers.get('Content-Length'))
     
@@ -231,7 +236,7 @@ async function pipeDecryptedStream(writer, body, length, bfKey) {
 }
 
 async function track_url(json, format) {
-    // needed if track has fallback, like https://www.deezer.com/track/1398759152
+    // needed if track has fallback, like https://www.deezer.com/track/11835714
     if (json.alternative) {
         json = json.alternative
     }