Require iOS 15 for Disable Infinite Scrolling

Fixes crash when refreshing on iOS 14

Tusker/Screens/Preferences/WellnessPrefsView.swift

@@ -16,8 +16,10 @@ struct WellnessPrefsView: View {
             showFavAndReblogCount
             notificationsMode
             grayscaleImages
+            if #available(iOS 15.0, *) {
                 disableInfiniteScrolling
             }
+        }
         .listStyle(InsetGroupedListStyle())
         .navigationBarTitle(Text("Digital Wellness"))
     }

Tusker/Screens/Timeline/TimelineTableViewController.swift

@@ -123,7 +123,8 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
             return
         }
         
-        guard !Preferences.shared.disableInfiniteScrolling || didConfirmLoadMore else {
+        if #available(iOS 15.0, *),
+           Preferences.shared.disableInfiniteScrolling && !didConfirmLoadMore {
             guard !currentSnapshot.itemIdentifiers(inSection: .footer).contains(.confirmLoadMore) else {
                 // todo: need something more accurate than "success"/"failure"
                 completion(.success(currentSnapshot))
@@ -177,11 +178,11 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
                 
                 self.mastodonController.persistentContainer.addAll(statuses: statuses) {
                     var snapshot = currentSnapshot
-                    let identifiers = statuses.map { Item.status(id: $0.id, state: .unknown) }
+                    let newIdentifiers = statuses.map { Item.status(id: $0.id, state: .unknown) }
                     if let first = snapshot.itemIdentifiers(inSection: .statuses).first {
-                        snapshot.insertItems(identifiers, beforeItem: first)
+                        snapshot.insertItems(newIdentifiers, beforeItem: first)
                     } else {
-                        snapshot.appendItems(identifiers, toSection: .statuses)
+                        snapshot.appendItems(newIdentifiers, toSection: .statuses)
                     }
                     completion(.success(snapshot))
                 }
@@ -205,6 +206,27 @@ extension TimelineTableViewController {
     enum Item: Hashable {
         case status(id: String, state: StatusState)
         case confirmLoadMore
+        
+        static func ==(lhs: Item, rhs: Item) -> Bool {
+            switch (lhs, rhs) {
+            case let (.status(id: a, state: _), .status(id: b, state: _)):
+                return a == b
+            case (.confirmLoadMore, .confirmLoadMore):
+                return true
+            default:
+                return false
+            }
+        }
+        
+        func hash(into hasher: inout Hasher) {
+            switch self {
+            case let .status(id: id, state: _):
+                hasher.combine(0)
+                hasher.combine(id)
+            case .confirmLoadMore:
+                hasher.combine(1)
+            }
+        }
     }
 }