[Flutter] justAudio used very simply per the example creates an Exception

I have completed an app using Just Audio. I built it following the example provided. I want to add background music. I thought I followed Ryan Heise's example for a simple player. I must be missing something. I receive the following Exception:

Exception has occurred. _TypeError (type 'Null' is not a subtype of type 'MediaItem' in type cast)

on this line:

await musicPlayer.setAudioSource(AudioSource.uri(Uri.parse(url)));

Here is the function that fails with this line:

Future<void> playBackgroundMusic() async {
int rng = Random().nextInt(7);
// Inform the operating system of our app's audio attributes etc.
// We pick a reasonable default for an app that plays speech.
final session = await AudioSession.instance;
await session.configure(const AudioSessionConfiguration.speech());
String musicFilename = filenameList[rng];
String url =
"MY_SERVER/music/$musicFilename";
final musicPlayer = AudioPlayer();
try {
await musicPlayer.setAudioSource(AudioSource.uri(Uri.parse(url)));
} on PlayerException catch (e) {
print("Error loading audio source: $e");
}
musicPlayer.play();
}



This function is called by the first initState in the app:

@override
void initState() {
super.initState();
playBackgroundMusic();
}


A similar question 78571039 was asked and the answer given was to import Audio Service and add this code:

AudioSource.uri( Uri.parse(item.music), tag: MediaItem( id: "${item.id}", album: "${musicImage}", title: "${item.name}", artUri: Uri.parse('${musicImage}'), ), ),


This solved my problem - but there is no way I would have known this from the Just Audio documentation. I think this indicates that something (documentation) or code needs to change in Just Audio. This problem was not solved on Github in September 2023 due to lack of specificity. https://github.com/ryanheise/just_audio/issues/991.

So I am asking either to be pointed to the existing documentation that says this import and line of code is required or to update the documentation. This is too good of a plugin to have something that would keep people from using it.

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