Remove direct accesses of MastodonController.instance

Fixes potential race conditions

Tusker/Screens/Explore/ExploreViewController.swift

@@ -57,10 +57,6 @@ class ExploreViewController: UIViewController, UICollectionViewDelegate, Collect
         dataSource = createDataSource()
         applyInitialSnapshot()
         
-        if mastodonController.instance == nil {
-            mastodonController.getOwnInstance(completion: self.ownInstanceLoaded(_:))
-        }
-        
         resultsController = SearchResultsViewController(mastodonController: mastodonController)
         resultsController.exploreNavigationController = self.navigationController!
         searchController = UISearchController(searchResultsController: resultsController)
@@ -79,6 +75,9 @@ class ExploreViewController: UIViewController, UICollectionViewDelegate, Collect
         NotificationCenter.default.addObserver(self, selector: #selector(savedInstancesChanged), name: .savedInstancesChanged, object: nil)
         NotificationCenter.default.addObserver(self, selector: #selector(preferencesChanged), name: .preferencesChanged, object: nil)
         
+        mastodonController.instanceFeatures.featuresUpdated
+            .sink { [unowned self] in self.instanceFeaturesChanged() }
+            .store(in: &cancellables)
         mastodonController.$lists
             .sink { [unowned self] in self.reloadLists($0) }
             .store(in: &cancellables)
@@ -194,7 +193,7 @@ class ExploreViewController: UIViewController, UICollectionViewDelegate, Collect
         snapshot.appendItems([.trends], toSection: .discover)
     }
     
-    private func ownInstanceLoaded(_ instance: Instance) {
+    private func instanceFeaturesChanged() {
         var snapshot = self.dataSource.snapshot()
         if mastodonController.instanceFeatures.trends,
            !snapshot.sectionIdentifiers.contains(.discover) {

Tusker/Screens/Main/MainSidebarViewController.swift

@@ -97,10 +97,6 @@ class MainSidebarViewController: UIViewController {
         
         applyInitialSnapshot()
         
-        if mastodonController.instance == nil {
-            mastodonController.getOwnInstance(completion: self.ownInstanceLoaded(_:))
-        }
-        
         select(item: .tab(.timelines), animated: false)
         
         NotificationCenter.default.addObserver(self, selector: #selector(reloadSavedInstances), name: .savedInstancesChanged, object: nil)
@@ -189,14 +185,6 @@ class MainSidebarViewController: UIViewController {
         reloadSavedInstances()
     }
     
-    private func ownInstanceLoaded(_ instance: Instance) {
-        let prevSelected = collectionView.indexPathsForSelectedItems
-        
-        if let prevSelected = prevSelected?.first {
-            collectionView.selectItem(at: prevSelected, animated: false, scrollPosition: .top)
-        }
-    }
-    
     private func reloadLists(_ lists: [List], animated: Bool) {
         if let selectedItem,
            case .list(let list) = selectedItem,

Tusker/Screens/Report/ReportView.swift

@@ -24,9 +24,6 @@ struct ReportView: View {
         self.account = mastodonController.persistentContainer.account(for: report.accountID)!
         self.mastodonController = mastodonController
         self._report = StateObject(wrappedValue: report)
-        if mastodonController.instance?.rules == nil {
-            report.reason = .spam
-        }
     }
     
     var body: some View {
@@ -173,6 +170,11 @@ struct ReportView: View {
                 }
             }
         }
+        .onReceive(mastodonController.$instance) { instance in
+            if instance?.rules == nil {
+                report.reason = .spam
+            }
+        }
     }
     
     private func sendReport() {