Make folder.account weak and optional.

Evergreen/MainWindow/AddFeed/AddFeedController.swift

@@ -147,8 +147,8 @@ private extension AddFeedController {
 		if let account = container as? Account {
 			return AccountAndFolderSpecifier(account: account, folder: nil)
 		}
-		if let folder = container as? Folder {
-			return AccountAndFolderSpecifier(account: folder.account, folder: folder)
+		if let folder = container as? Folder, let account = folder.account {
+			return AccountAndFolderSpecifier(account: account, folder: folder)
 		}
 		return nil
 	}

Evergreen/MainWindow/Sidebar/SidebarViewController.swift

@@ -194,8 +194,8 @@ private extension SidebarViewController {
 			if let feed = object as? Feed, let account = feed.account {
 				account.updateUnreadCounts(for: Set([feed]))
 			}
-			else if let folder = object as? Folder {
-				folder.account.updateUnreadCounts(for: folder.flattenedFeeds())
+			else if let folder = object as? Folder, let account = folder.account {
+				account.updateUnreadCounts(for: folder.flattenedFeeds())
 			}
 		}
 	}

Frameworks/Account/Folder.swift

@@ -11,7 +11,7 @@ import Data
 
 public final class Folder: DisplayNameProvider, Container, UnreadCountProvider {
 
-	public let account: Account
+	public weak var account: Account?
 	public var children = [AnyObject]()
 	var name: String?
 	static let untitledName = NSLocalizedString("Untitled ƒ", comment: "Folder name")
@@ -19,7 +19,10 @@ public final class Folder: DisplayNameProvider, Container, UnreadCountProvider {
 	// MARK: - Fetching Articles
 	
 	public func fetchArticles() -> Set<Article> {
-		
+
+		guard let account = account else {
+			return Set<Article>()
+		}
 		return account.fetchArticles(folder: self)
 	}
 	
@@ -76,7 +79,11 @@ public final class Folder: DisplayNameProvider, Container, UnreadCountProvider {
 
 	var dictionary: [String: Any] {
 		get {
+
 			var d = [String: Any]()
+			guard let account = account else {
+				return d
+			}
 
 			if let name = name {
 				d[Key.name] = name