Use correct account method for adding folders

Frameworks/Account/Account.swift

@@ -426,7 +426,7 @@ public final class Account: DisplayNameProvider, UnreadCountProvider, Container,
 	}
 
 	@discardableResult
-	public func ensureFolder(with name: String) -> Folder? {
+	func ensureFolder(with name: String) -> Folder? {
 		// TODO: support subfolders, maybe, some day
 
 		if name.isEmpty {

Mac/MainWindow/AddFolder/AddFolderWindowController.swift

@@ -72,7 +72,15 @@ class AddFolderWindowController : NSWindowController {
 			return
 		}
 		
-		account.ensureFolder(with: folderName)
+		account.addFolder(folderName) { result in
+			switch result {
+			case .success:
+				break
+			case .failure(let error):
+				NSApplication.shared.presentError(error)
+			}
+		}
+			
 	}
 	
 	// MARK: Actions

Mac/Scriptability/Folder+Scriptability.swift

@@ -76,11 +76,20 @@ class ScriptableFolder: NSObject, UniqueIdScriptingObject, ScriptingObjectContai
             print("support for folders within folders is NYI");
             return nil
         }
-        let scriptableAccount = ScriptableAccount(account)        
-        if let newFolder = account.ensureFolder(with:name) {
-            let scriptableFolder = ScriptableFolder(newFolder, container:scriptableAccount)
-            return(scriptableFolder.objectSpecifier)
-        }
+		
+		command.suspendExecution()
+		
+		account.addFolder(name) { result in
+			switch result {
+			case .success(let folder):
+				let scriptableAccount = ScriptableAccount(account)
+				let scriptableFolder = ScriptableFolder(folder, container:scriptableAccount)
+				command.resumeExecution(withResult:scriptableFolder.objectSpecifier)
+			case .failure:
+				command.resumeExecution(withResult:nil)
+			}
+		}
+		
         return nil
     }
     

NetNewsWire.xcodeproj/xcshareddata/xcschemes/NetNewsWire.xcscheme

@@ -28,6 +28,16 @@
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
       shouldUseLaunchSchemeArgsEnv = "YES">
       <Testables>
+         <TestableReference
+            skipped = "NO">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "849C64701ED37A5D003D8FC0"
+               BuildableName = "NetNewsWireTests.xctest"
+               BlueprintName = "NetNewsWireTests"
+               ReferencedContainer = "container:NetNewsWire.xcodeproj">
+            </BuildableReference>
+         </TestableReference>
       </Testables>
    </TestAction>
    <LaunchAction