Getting Error 500 while trying to add items to a playlist.

[germanJR_DEV]

Plan

Premium

Country

Spain (ES)

Device

Desktop computer

Operating System

Linux mint 20.2

My Question or Issue

I was trying to add some tracks to one of my playlists, and I keep getting the following error response:

{"error": {"status": 500, "message": "com.schibsted.spt.data.jslt.JsltException: For loop can't iterate over "uris=spotify:track:5yj8QDJ967St7PUG7sFD0n,spotify:track:7ppZPegqYaJszeylK41PfR" at <unknown>:18:7" } }

Here is the code that calls the API:

export async function addItemsToPlaylist(accessToken, userId, playlistId, uris) {
    const formattedUris = "uris=" + uris.split(',').map(id => `spotify:track:${id}`);
    console.log(formattedUris)

    const response = await fetch(`https://api.spotify.com/v1/playlists/${playlistId}/tracks`, {
        method: 'POST',
        headers: {
            Authorization: 'Bearer ' + accessToken,
            'Content-Type': 'application/json'
        },
        body: JSON.stringify({
            uris: formattedUris,
        })
    });
    if (!response.ok) {
        console.log( await response.text())
        throw new Error("Error! Could not add items to playlist: " + await response.text())
    }
    return await response.json();
}

Is something wrong with the treatment of the IDs? How can I fix the error?