Crashing on exception: executeFetchRequest:error: A fetch request must have an entity.

I am trying to display a simple list of text based on an NSManagedObject subclass. In this class, I am not doing any fetch requests, I am simply passing in a list that was already fetched.

When trying to preview this view, the preview keeps crashing and I can't figure out why. It does not crash when this view is created as a subview in another preview.

Code Block Swift
import SwiftUI
struct TracksView: View {
    var songs: [Song] = []
   
    var body : some View {
        List(songs.map{$0.title!}, id:
                \.self){(song:String) in
            Text(song)
        }
    }
}
struct TracksView_Previews: PreviewProvider {
    static var context = PersistenceController.preview.container.viewContext
    static var songs: [Song] = {
        let req = NSFetchRequest<NSFetchRequestResult>(entityName: Song.className())
        var s:[Song]?
        do {
            let data = try context.fetch(req)
            if data.first! is Song{
                s = data as? [Song]
            }
        } catch {
            print(error.localizedDescription)
        }
return s ?? []
    }()
    static let env = Global()
    static var previews: some View {
        TracksView(songs: songs)
            .environment(\.managedObjectContext, context)
            .environmentObject(env)
    }
}