I was using the Web API to call the Playlist tracks (by way of
"https://api.spotify.com/v1/playlists/<playlist_id>/tracks"). All my playlists except this one (https://open.spotify.com/playlist/37i9dQZF1DWVzlTZFHBHNN) could not decode. Upon further inspection, I saw the raw JSON data (image attached), and saw that the first object looked like a boiler plate with no information regarding an example.
Luckily, I just made certain values in my JSON decoding optional to fix this, particularly the "track" property in each data item.