CoreData bug in Xcode 12.1

If you are using SwiftUI lifecycle, you should initialize NSPersistentContainer in a parent View (or App) and import managedObjectContext to the environment.

In your case, it could be something like this:

import SwiftUI
import CoreData

@main
struct coreDataParadigmApp: App {
    let persistenceController = PersistenceController.shared
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environment(\.managedObjectContext, persistenceController.container.viewContext)
        }
    }
}


struct ContentView: View {
    @FetchRequest(entity: Student.entity(), sortDescriptors: []) var students: FetchedResults<Student>
    var body: some View {
        VStack {
            List {
                ForEach(students, id: \.id) { student in
                    Text(student.name ?? "Unknown")
                }
            }
        }
    }
 }

// DONT FORGET TO CHANGE THE NAME OF YOUR FILE
struct PersistenceController {
    static let shared = PersistenceController()

    let container: NSPersistentContainer

    init() {
        container = NSPersistentContainer(name: "coreDataNameOfFile")

        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
    }
}