SwiftUIとCoreData使用中にFatal error: Environment<NSManagedObjectContext> has no key-pathエラーが発生

Question

SwiftUIにてCoreDataを使用しています｡
なんの問題もなく使用できていたのですが､突然タイトルに有るエラーが発生しました｡
FetchRequestでKeyPathは指定しています｡
エラーはAppDelegateにて発生しています｡

可能性として考えられる原因をご教授いただければと思います｡
よろしくお願いいたします｡

import UIKit
import CoreData


@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate { //ここにエラーが引いてあります

    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
       
        
        return true
    }

    

    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }

    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
       application:didFinishLaunchingWithOptions.
       
    }
    
   

       lazy var persistentContainer: NSPersistentContainer = {
           
           let container = NSPersistentContainer(name: "coredata")
           container.loadPersistentStores(completionHandler: { (storeDescription, error) in
               if let error = error as NSError? {
                   
                    
                  
                   fatalError("Unresolved error (error), (error.userInfo)")
               }
           })
           return container
       }()

      

       func saveContext () {
           let context = persistentContainer.viewContext
           if context.hasChanges {
               do {
                   try context.save()
               } catch {
                  function in a shipping application, although it may be useful during development.
                   let nserror = error as NSError
                   fatalError("Unresolved error (nserror), (nserror.userInfo)")
               }
           }
       }



}

アプリ操作上､実際にエラーが出るのは以下のViewです｡

import SwiftUI
import CoreData

struct BtNameView:View {
    
    @State var nameOfBt:String
    
    var body: some View{
        HStack{
            Text("(nameOfBt)").frame(width: UIScreen.screenWidth/5)
            Divider()
        }
    }
}


struct DayDetailView: View {
    
    @Environment(.managedObjectContext) var managedObjectContext
    
    @FetchRequest(
        entity: BtList.entity(),
        sortDescriptors: [NSSortDescriptor(keyPath:\BtList.saveDate,ascending:true)],
        predicate: NSPredicate(format:"isComplete == %@ " ,NSNumber(value:false))
    )
    var DayDetailLists:FetchedResults<BtList>
    
    @Binding var doneBtDate:String
    
    var dateFormatter:DateFormatter{
        let formatter = DateFormatter()
        formatter.setLocalizedDateFormatFromTemplate("yMMMMdEEEE")
        
        return formatter
    }
    
    var saveDateFormatter:DateFormatter{
        let saveFormatter = DateFormatter()
        saveFormatter.setLocalizedDateFormatFromTemplate("yMMMMd")
        
        return saveFormatter
    }
    
    @State var btDictionary:[String:[String]] = [
        "BUN":[],
      // 一部略
    ]
    
    
    @State var btListBool = false
    @State var showBtListButtonBool = true
    
    @State var photoImage:Data = UIImage(imageLiteralResourceName: "grey-icon").pngData()!
    @State var photoTitle:String = ""
    
    var imageWidth = UIScreen.main.bounds.width*4/10
    var imageheight = UIScreen.main.bounds.width*4/10*4/3
    
    @State var zoomAppear = false
    
    
    var body: some View {
        
        VStack{
            padding()
            Text("(self.doneBtDate)").font(.caption).foregroundColor(.gGreen)
            Divider()
//            Text("画像一覧").font(.title)
            ScrollView(.horizontal,showsIndicators: false){
                HStack{
                    ForEach(DayDetailLists){photolist in
                        if (self.dateFormatter.string(from:photolist.saveDate ?? Date()) == self.doneBtDate && photolist.imageData != nil){
                            ZStack{
                                
                                Image(uiImage:UIImage(data:photolist.imageData ?? self.photoImage)!)
                                    .resizable()
                                    .frame(width:self.imageWidth,height:self.imageheight )
                                    .cornerRadius(6)
                                    .onTapGesture {
                                        self.photoImage = photolist.imageData ?? self.photoImage
                                        self.photoTitle = photolist.phototitle ?? ""
                                        self.zoomAppear.toggle()
                                        
                                }
                                .sheet(isPresented: self.$zoomAppear){ PhotoZoomView(zoomPhotoImage:self.$photoImage,zoomPhotoTitle: self.$photoTitle)
                                }
                                
                                    Text("(photolist.phototitle ?? "")").foregroundColor(.white)
                             
                            }//ZStack
                        }//if
                    }//ForEach
                }//HStack
            }//ScrolView
            
            if(self.btListBool == false && self.showBtListButtonBool == false){
                           Divider()
                           Button(action:{
                               self.btListBool = true
                           }){
                               Text("血液検査項目を開く")
                           }
                           Spacer()
                       }
                       
            
            List{
                Section(header:Text("メモ")){
                    ForEach(DayDetailLists){messagelist in
                        if(self.dateFormatter.string(from:messagelist.saveDate ?? Date()) == self.doneBtDate && messagelist.message != nil){
                            Text("(messagelist.message ?? "error")")
                        }
                    }
                }//Section
            }//List
            
            
            //            Divider()
            
           
            
            if(self.showBtListButtonBool){
                Divider()
                Button(action:{
                    for list in self.DayDetailLists{
                        print("(self.dateFormatter.string(from:list.saveDate ?? Date()))")
                        print("(self.doneBtDate)")
                        if self.dateFormatter.string(from:list.saveDate ?? Date()) == self.doneBtDate{
                            print("date success")
                            if let bun = list.bun{
                                self.btDictionary["BUN"]?.append("(bun)")
                            }else{
                                print("bun is Empty")
                            }
                           //一部略
                            
                            
                            self.btListBool = true
                            self.showBtListButtonBool = false
                        }//if
                        else{
                            print("date error")
                        }
                    }//for in
                }){
                    Text("血液検査結果を見る")
                }
                Spacer()
            }//if
            
           
            
            if(self.btListBool){
                VStack{
                    Divider()
                    Button(action:{
                        self.btListBool = false
                    }){Text("血液検査項目を閉じる")}
                    Form{
                        
                        Group{
                            
                            if self.btDictionary["BUN"]?.isEmpty ?? false{}
                            else{
                                BtDayListView(btDayListDictionary: self.btDictionary["BUN"] ?? ["error"], btDayListSection: "BUN", btDayListUnits: BtListView().kidneyUnits["BUN"] ?? "error")
                            }//else
                            
                           //一部略
                           
                        }//Group
                        
                    }//form
                    
                    
                    
                }//VStack
                
            }//if
            
        }//VStack
    }//body
}//View

struct BtDayListView:View{
    
   //略
}




コード