ios – Core Information unrecognized selector despatched to occasion when attempting to entry a NSSet property

I’m attempting to make an inventory of all TestItem objects however I get this error:
'NSInvalidArgumentException', purpose: '-[TestItem copyWithZone:]: unrecognized selector despatched to occasion.

Information mannequin

TestItem

TestItemList

TestItemList+CoreDataProperties

import Basis
import CoreData


extension TestItemList {

    @nonobjc public class func fetchRequest() -> NSFetchRequest<TestItemList> {
        return NSFetchRequest<TestItemList>(entityName: "TestItemList")
    }

    @NSManaged public var title: String?
    @NSManaged public var testitems: NSSet?
    
    public var itemArray: [TestItem] {
        let set = testitems as? Set<TestItem> ?? []
        return set.sorted{
            $0.title! < $1.title!
        }
    }

}

extension TestItemList : Identifiable {
}

ContentView

import SwiftUI
import CoreData

struct ContentView: View {
    @Atmosphere(.managedObjectContext) personal var viewContext

    @FetchRequest(
        sortDescriptors: [NSSortDescriptor(keyPath: TestItemList.name, ascending: true)],
        animation: .default)
    personal var itemLists: FetchedResults<TestItemList>

    @State var listExists: Bool = false
    
    var physique: some View {
        NavigationView {
            VStack{
                Record{
                    ForEach(itemLists, id: .self){ Record in
                        NavigationLink(vacation spot: ListElementsView(record: Record)){
                            Textual content("(Record.title!)")
                        }
                    }.onDelete(carry out: deleteItemList)
                }
                if(listExists){
                    Textual content("Record exists!").foregroundColor(.pink)
                }
                Button("Add at the moment's record", motion: {
                    addItemList()
                }).disabled(listExists).buttonStyle(.borderedProminent)
                Record{
                    ForEach(testitems){
                        merchandise in Textual content("(merchandise.title!), (merchandise.record!.title!)")
                    }
                }
            }
        }
    }
    
    personal func addItemList() {
        let dateFormatter : DateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd"
        let date = Date()
        let dateString = dateFormatter.string(from: date)
        
        
        if(!itemLists.comprises(the place: {$0.title == dateString})){
            let newList = TestItemList(context: viewContext)
            newList.title = dateString
            
            do{
                attempt viewContext.save()
            } catch {
                let error = error as NSError
                fatalError("Error (error), (error.userInfo)")
            }
        }else{
            listExists = true
        }
    }

    personal func deleteItemList(offsets: IndexSet) {
        withAnimation {
            offsets.map { itemLists[$0] }.forEach(viewContext.delete)

            do {
                attempt viewContext.save()
            } catch {
                let nsError = error as NSError
                fatalError("Unresolved error (nsError), (nsError.userInfo)")
            }
        }
    }
}

personal let itemFormatter: DateFormatter = {
    let formatter = DateFormatter()
    formatter.dateStyle = .brief
    formatter.timeStyle = .medium
    return formatter
}()

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView().surroundings(.managedObjectContext, PersistenceController.preview.container.viewContext)
    }
}

ListElementsView

import SwiftUI

struct ListElementsView: View {
    @Atmosphere (.managedObjectContext) personal var viewContext
    
    @FetchRequest(sortDescriptors: [NSSortDescriptor(keyPath: TestItem.name, ascending: true)], animation: .default)
    personal var testitems: FetchedResults<TestItem>

    var record: TestItemList
    
    @State personal var textual content: String = ""
    
    var inputNotOk: Bool{
        textual content.isEmpty
    }
    
    var physique: some View {
        VStack{
            Textual content(record.title!).font(.largeTitle)
            Record{
                ForEach(record.itemArray){
                    obj in Textual content("(obj.title!)")
                }.onDelete(carry out: deleteTestItem)
            }
            Button("Add merchandise", motion: {
                addNewTestItem()
            }).disabled(inputNotOk).buttonStyle(.borderedProminent)
            TextField("merchandise title", textual content: $textual content)
        }
    }
    
    personal func addNewTestItem(){
        let newItem = TestItem(context: viewContext)
        newItem.title = textual content
        newItem.record = record
        do{
            attempt viewContext.save()
        } catch {
            let error = error as NSError
            fatalError("Error (error), (error.userInfo)")
        }
    }
    
    personal func deleteTestItem(offsets: IndexSet){
        withAnimation{
            offsets.map{testitems[$0]}.forEach(viewContext.delete)
        }
        do{
            attempt viewContext.save()
        } catch {
            let error = error as NSError
            fatalError("Error (error), (error.userInfo)")
        }
    }
}

If the record has objects, the app crashes when i enter ListElementsView. I can enter it if the record is empty.

I attempted doing print(sort(of: record.testitems)), it returns NSSet

Then i attempted including print(record.testitems!.depend), the app crashes.

Any concepts?