Core Data template app generates errors on save - macos

Question

While evaluating Core Data for a macOS app, I get errors logged to the console when the document is saved:
[logging-persist] cannot open file at line 39930 of [02c344acea]
[logging-persist] os_unix.c:39930: (0) openDirectory(/Users/seanrich/Desktop) - Undefined error: 0
The data is saved properly and there's no other indication of an issue, but that error is concerning.
This sample project demonstrates the issue. It's minimally changed from a template project (selecting SwiftUI as the interface, Core Data checked). There's a single entity, Item, with a single attribute, name. I added a minimal interface to add items into the NSManagedObjectContext:
struct ContentView: View {
#State private var name = ""
#Environment(\.managedObjectContext) var moc
#FetchRequest(entity: Item.entity(), sortDescriptors: [.byName]) var items: FetchedResults<Item>
var body: some View {
VStack {
HStack {
TextField("Name", text: $name)
Button("New") {
let item = Item(context: moc)
item.name = name
}
}
.padding()
VStack {
ForEach(items) { item in
Text(item.name ?? "No name")
}
}
Spacer()
}
.frame(maxWidth: .infinity, maxHeight: .infinity)
}
}
The NSPersistentDocument subclass is unchanged from the template:
EDIT: I added a line to explicitly load the managedObjectModel or the SwiftUI view tries to fetch an entity that isn't there yet:
class Document: NSPersistentDocument {
override class var autosavesInPlace: Bool { true }
override func makeWindowControllers() {
_ = managedObjectModel
let contentView = ContentView().environment(\.managedObjectContext, self.managedObjectContext!)
// Create the window and set the content view.
let window = NSWindow(
contentRect: NSRect(x: 0, y: 0, width: 480, height: 300),
styleMask: [.titled, .closable, .miniaturizable, .resizable, .fullSizeContentView],
backing: .buffered, defer: false)
window.isReleasedWhenClosed = false
window.center()
window.contentView = NSHostingView(rootView: contentView)
let windowController = NSWindowController(window: window)
self.addWindowController(windowController)
}
}
I thought it might be a permissions issue, but the sandbox is set to give read/write access to user-selected files. Couldn't find any mention of this issue anywhere which is surprising since it seems to be default behavior. Makes me think I'm missing something obvious.