Fix crash when trying to load deleted statuses for restoration

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -334,25 +334,31 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
             return false
         }
         loadViewIfNeeded()
+        var loaded = false
         await controller.restoreInitial {
-            await loadStatusesToRestore(position: position)
-            applyItemsToRestore(position: position)
+            let hasStatusesToRestore = await loadStatusesToRestore(position: position)
+            if hasStatusesToRestore {
+                applyItemsToRestore(position: position)
+                loaded = true
+            }
         }
-        return true
+        return loaded
     }
     
     @MainActor
-    private func loadStatusesToRestore(position: TimelinePosition) async {
+    private func loadStatusesToRestore(position: TimelinePosition) async -> Bool {
         let unloaded = position.statusIDs.filter({ mastodonController.persistentContainer.status(for: $0) == nil })
         guard !unloaded.isEmpty else {
-            return
+            return true
         }
         let statuses = await withTaskGroup(of: Status?.self) { group -> [Status] in
             for id in unloaded {
-                group.addTask { @MainActor in
-                    if let (status, _) = try? await self.mastodonController.run(Client.getStatus(id: id)) {
+                group.addTask {
+                    do {
+                        let (status, _) = try await self.mastodonController.run(Client.getStatus(id: id))
                         return status
-                    } else {
+                    } catch {
+                        print(error)
                         return nil
                     }
                 }
@@ -364,6 +370,20 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
             }
         }
         await mastodonController.persistentContainer.addAll(statuses: statuses, in: mastodonController.persistentContainer.viewContext)
+        
+        // update the timeline position in case some statuses couldn't be loaded
+        if let center = position.centerStatusID {
+            let nearestLoadedStatusToCenter = position.statusIDs[position.statusIDs.firstIndex(of: center)!...].first(where: { id in
+                // was already loaded or was just now loaded
+                !unloaded.contains(id) || statuses.contains(where: { $0.id == id })
+            })
+            position.centerStatusID = nearestLoadedStatusToCenter
+        }
+        position.statusIDs = position.statusIDs.filter { id in
+            !unloaded.contains(id) || statuses.contains(where: { $0.id == id })
+        }
+        
+        return !position.statusIDs.isEmpty
     }
     
     private func applyItemsToRestore(position: TimelinePosition) {