Harden against sync changes.

Client.xcodeproj/project.pbxproj

@@ -87,6 +87,7 @@
 		0AEFB84922244135007AF600 /* AdblockDebugMenuTableViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0AEFB84822244135007AF600 /* AdblockDebugMenuTableViewController.swift */; };
 		0AEFB8532226D7C5007AF600 /* AdblockResourcesMappings.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0AEFB8522226D7C5007AF600 /* AdblockResourcesMappings.swift */; };
 		0AEFB88722299E6A007AF600 /* AdblockerType.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0AEFB88622299E6A007AF600 /* AdblockerType.swift */; };
+		0AF0411B2267C61100EBF982 /* ManagedObjectExtensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0AF0411A2267C61100EBF982 /* ManagedObjectExtensions.swift */; };
 		0AF3B4ED213D8E3300695962 /* CoreDataTestCase.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0AF3B4E5213D8E3200695962 /* CoreDataTestCase.swift */; };
 		0AF3B4EE213D8E3300695962 /* HistoryTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0AF3B4E6213D8E3200695962 /* HistoryTests.swift */; };
 		0AF3B4EF213D8E3300695962 /* DomainTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0AF3B4E7213D8E3200695962 /* DomainTests.swift */; };
@@ -1210,6 +1211,7 @@
 		0AEFB84822244135007AF600 /* AdblockDebugMenuTableViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AdblockDebugMenuTableViewController.swift; sourceTree = "<group>"; };
 		0AEFB8522226D7C5007AF600 /* AdblockResourcesMappings.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AdblockResourcesMappings.swift; sourceTree = "<group>"; };
 		0AEFB88622299E6A007AF600 /* AdblockerType.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AdblockerType.swift; sourceTree = "<group>"; };
+		0AF0411A2267C61100EBF982 /* ManagedObjectExtensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ManagedObjectExtensions.swift; sourceTree = "<group>"; };
 		0AF3B4E5213D8E3200695962 /* CoreDataTestCase.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = CoreDataTestCase.swift; sourceTree = "<group>"; };
 		0AF3B4E6213D8E3200695962 /* HistoryTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = HistoryTests.swift; sourceTree = "<group>"; };
 		0AF3B4E7213D8E3200695962 /* DomainTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DomainTests.swift; sourceTree = "<group>"; };
@@ -3255,6 +3257,7 @@
 				5D1DC51520AC9AFA00905E5A /* Data.h */,
 				5D1DC51620AC9AFA00905E5A /* Info.plist */,
 				59B6912721B695A400E9388E /* InfoPlist.strings */,
+				0AF0411A2267C61100EBF982 /* ManagedObjectExtensions.swift */,
 			);
 			indentWidth = 4;
 			path = Data;
@@ -5431,6 +5434,7 @@
 				5D1DC57220AE005400905E5A /* JSInjector.swift in Sources */,
 				5D1DC55920AE004600905E5A /* Bookmark.swift in Sources */,
 				5D1DC55B20AE004600905E5A /* Domain.swift in Sources */,
+				0AF0411B2267C61100EBF982 /* ManagedObjectExtensions.swift in Sources */,
 				0AA4FC392109D685000B173A /* CRUDProtocols.swift in Sources */,
 				5D1DC56B20AE005400905E5A /* SyncCrypto.swift in Sources */,
 				5D1DC55F20AE004600905E5A /* Model.xcdatamodeld in Sources */,

Client/Frontend/Browser/Toolbars/BottomToolbar/Menu/AddEditBookmarkTableViewController.swift

@@ -64,6 +64,17 @@ class AddEditBookmarkTableViewController: UITableViewController {
             }
         }
 
+        /// Making sure the folder we are saving to still exists.
+        /// This could happen if the folder got deleted by another device in sync chain.
+        var exists: Bool {
+            // Root level and favorites locations are permanent, only custom folder needs to be checked.
+            switch self {
+            case .folder(let folder):
+                return folder.existsInPersistentStore()
+            default:
+                return false
+            }
+        }
     }
 
     private enum DataSourcePresentationMode {
@@ -81,10 +92,6 @@ class AddEditBookmarkTableViewController: UITableViewController {
     }
 
     let frc: NSFetchedResultsController<Bookmark>
-
-    //let action: AddEditBookmarkTableViewController.Action
-    //let type: AddEditBookmarkTableViewController.BookmarkType
-    
     let mode: AddEditBookmarkTableViewController.Mode
 
     lazy var saveButton: UIBarButtonItem = {
@@ -140,10 +147,6 @@ class AddEditBookmarkTableViewController: UITableViewController {
         tableView.contentInset = UIEdgeInsets(top: 36, left: 0, bottom: 0, right: 0)
 
         frc.delegate = self
-        try? frc.performFetch()
-        sortedFolders = sortFolders()
-
-        tableView.reloadData()
 
         switch mode {
         case .newBookmark(_, _): title = Strings.NewBookmarkTitle
@@ -155,6 +158,20 @@ class AddEditBookmarkTableViewController: UITableViewController {
 
     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
+        reloadData()
+    }
+
+    func reloadData() {
+        try? frc.performFetch()
+        sortedFolders = sortFolders()
+
+        // If the bookmark we save to was deleted, UI needs an update
+        // and a fallback location.
+        if !location.exists {
+            location = .rootLevel
+        }
+
+        tableView.reloadData()
     }
 
     typealias IndentedFolder = (Bookmark, indentationLevel: Int)
@@ -203,6 +220,10 @@ class AddEditBookmarkTableViewController: UITableViewController {
 
         guard let title = bookmarkDetailsView.titleTextField.text else { return earlyReturn() }
 
+        if !location.exists {
+            location = .rootLevel
+        }
+
         switch mode {
         case .newBookmark(_, _):
             guard let urlString = bookmarkDetailsView.urlTextField?.text,
@@ -235,6 +256,8 @@ class AddEditBookmarkTableViewController: UITableViewController {
                     return earlyReturn()
             }
 
+            if !bookmark.existsInPersistentStore() { break }
+
             switch location {
             case .rootLevel:
                 bookmark.updateWithNewLocation(customTitle: title, url: urlString, location: nil)
@@ -246,6 +269,7 @@ class AddEditBookmarkTableViewController: UITableViewController {
             }
 
         case .editFolder(let folder):
+            if !folder.existsInPersistentStore() { break }
 
             switch location {
             case .rootLevel:
@@ -425,9 +449,6 @@ extension AddEditBookmarkTableViewController: NSFetchedResultsControllerDelegate
     func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChange anObject: Any, at indexPath: IndexPath?, for type: NSFetchedResultsChangeType, newIndexPath: IndexPath?) {
 
         // Possible performance bottleneck
-        try? frc.performFetch()
-        sortedFolders = sortFolders()
-
-        tableView.reloadData()
+        reloadData()
     }
 }

Data/ManagedObjectExtensions.swift

@@ -0,0 +1,17 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import Foundation
+import CoreData
+
+public extension NSManagedObject {
+    /// Returns true if the object still exists in the persistent store.
+    func existsInPersistentStore() -> Bool {
+        // `isDeleted` is set to true if the object is going to be deleted
+        // on the next context save.
+        // After the save happens, managedObjectContext is set to nil.
+        // This conditional should catch both deletion states.
+        return !isDeleted && managedObjectContext != nil
+    }
+}

Data/models/Bookmark.swift

@@ -523,7 +523,9 @@ extension Bookmark {
             if isFolder {
                 removeFolderAndSendSyncRecords(uuid: syncUUID)
             } else {
-                Sync.shared.sendSyncRecords(action: .delete, records: [self])
+                DataController.perform(context: context) { context in
+                    Sync.shared.sendSyncRecords(action: .delete, records: [self], context: context)
+                }
             }
         }
 
@@ -547,7 +549,7 @@ extension Bookmark {
                 allBookmarks.append(contentsOf: allNestedBookmarks)
             }
 
-            Sync.shared.sendSyncRecords(action: .delete, records: allBookmarks)
+            Sync.shared.sendSyncRecords(action: .delete, records: allBookmarks, context: context)
 
             bookmarkOnCorrectContext.deleteInternal(context: .existing(context))
         }