SwiftUI:Context in environment is not connected to a persistent store coordinator:

現在SwiftUIとCoreDataを利用して､データの保存アプリを作成しています｡
データ保存画面で値を入力したあと､確認画面を開く際にアプリがクラッシュします｡
シュミレーター上では問題ないのですが､実機で行い際にクラッシュします｡
原因がわからないのでご指導お願いします｡

データ保存画面↓

swift
1
2//
3//  BtListView.swift
4
5
6import SwiftUI
7import CoreData
8
9
10
11struct BtListView: View {
12    
13    @Environment(.managedObjectContext) var context
14    @ObservedObject var keyboard = KeyboardObserver()
15    
16    func addBun(){
17        let newBun = BtList(context:context)
18        newBun.id = UUID()
19        newBun.isComplete = false
20        if bunValue != ""{ //入力無しでボタンを押した場合の条件分類
21            newBun.bun = bunValue
22        }
23        newBun.saveDate = Date()
24        do{
25            try context.save()
26        }catch{
27            print(error)
28        }
29    }
30   
31   
32    @State var bunValue:String = ""
33    @State var creValue:String = ""
34    
35    
36    let kidneys = ["BUN","CRE"]
37    
38    
39    let kidneyUnits = ["BUN":"mg/dL","CRE":"mg/dL"]
40    
41    
42    let kidneyBtCriteria = ["BUN":"6-25","CRE":"0.5-1.6"]
43   
44    
45    var body: some View {
46        
47        List{
48            Section(header:Text("腎機能")){
49                
50                HStack{
51                                ListFirstContainer(categoryName: kidneys[0])
52                    TextField("数字を入力",text:self.$bunValue)
53                                    .keyboardType(.numberPad)
54                    ListSecondContainer(btUnitValue: kidneyUnits["BUN"] ?? "error", btCriteriaValue: kidneyBtCriteria["BUN"] ?? "error")
55                    Button(action:{
56                        self.addBun()
57                        UIApplication.shared.endEditing()
58                        }){
59                        Text("追加")
60                    }
61                }
62                    
63                HStack{
64                    ListFirstContainer(categoryName: kidneys[1])
65                    TextField("数字を入力",text: self.$creValue)
66                        .keyboardType(.numberPad)
67                    ListSecondContainer(btUnitValue: kidneyUnits["CRE"] ?? "error", btCriteriaValue: kidneyBtCriteria["CRE"] ?? "error")
68                    Button(action:{
69                        self.addCre()
70                        UIApplication.shared.endEditing()
71                    }
72                    ){
73                        Text("追加")
74                    }
75                }
76            }//Sectionの閉じ
77            
78                    }//Listの閉じ
79                    .onAppear{
80                        self.keyboard.startObserve()
81                    }.onDisappear{
82                        self.keyboard.stopObserve()
83                    }.padding(.bottom,keyboard.keyboardHeight)
84                        .animation(.easeOut)
85            }//bodyの閉じ
86        }//structの閉じ
87        
88
89
90
91struct BtListView_Previews: PreviewProvider {
92    static var previews: some View {
93        BtListView()
94    }
95}
96

データ表示画面↓(エラーが出ているのがこのファイルです)

swift
1
2//  showBunValue.swift
3
4
5import SwiftUI
6import CoreData
7
8struct showBunValue:View {
9    
10    
11    
12    @FetchRequest(
13       entity: BtList.entity(),
14       sortDescriptors: [NSSortDescriptor(keyPath:\BtList.saveDate,ascending:false)],
15       predicate: NSPredicate(format:"isComplete == %@",NSNumber(value:false))
16       )
17       var notCompletedBunLists:FetchedResults<BtList>
18       
19    
20    var body:some View {
21        List{
22            Section(header:Text("結果|基準値|単位")){
23            ForEach(notCompletedBunLists){list in
24              if list.bun as? String != nil{
25                    HStack{
26                BunValueList(btList:list)
27                        ListSecondContainer(btUnitValue: BtListView().kidneyUnits["BUN"] ?? "error", btCriteriaValue: BtListView().kidneyBtCriteria["BUN"] ?? "error")
28                    }
29              }else{
30                Text("error")
31                }
32                }
33            }
34        }
35    }
36}
37
38struct showBunValue_Previews: PreviewProvider {
39    static var previews: some View {
40        showBunValue()
41    }
42}
43