Fix the iPad which seems to like to set the selected value to nil after setting it to the correct selection

Multiplatform/Shared/Sidebar/SidebarModel.swift

@@ -91,11 +91,11 @@ private extension SidebarModel {
 		}
 		.assign(to: $selectedFeeds)
 		
-		$selectedFeedIdentifier.map { [weak self] feedID in
+		$selectedFeedIdentifier.compactMap { [weak self] feedID in
 			if let feedID = feedID, let feed = self?.findFeed(feedID) {
 				return [feed]
 			} else {
-				return [Feed]()
+				return nil
 			}
 		}
 		.assign(to: $selectedFeeds)

Multiplatform/Shared/Timeline/TimelineModel.swift

@@ -131,11 +131,11 @@ class TimelineModel: ObservableObject, UndoableCommandRunner {
 		}
 		.assign(to: $selectedArticles)
 		
-		$selectedArticleID.map { [weak self] articleID in
+		$selectedArticleID.compactMap { [weak self] articleID in
 			if let articleID = articleID, let article = self?.idToArticleDictionary[articleID] {
 				return [article]
 			} else {
-				return [Article]()
+				return nil
 			}
 		}
 		.assign(to: $selectedArticles)