SwiftData Fatal error: failed to find a currently active container

I'm new to Apple development and decided to learn using SwiftData and Xcode 15 beta 4 (though I'm starting to think I don't need that extra challenge). I've worked through many issues--with you all's help--but this is one I can't figure out and hasn't shown up in my searches.

I'm working on the traditional task list app (with a Task model). I've tried several approaches to app structure, but each time I eventually hit this same error. It doesn't happen when I set up the new Xcode project, but eventually it does. I've cleaned the build folder, restarted the Simulator, and even rebooted the Macbook I'm working on.

Here's what happens when I click Product > Run:

• the app builds successfully

• the Simulator displays a white screen as expected

• then the error appears.

Here are the error messages:

In the debug area it says:

SwiftData/ModelContainer.swift:159: Fatal error: failed to find a currently active container for Task
Failed to find any currently loaded container for Task)

and in the warning in the editor says Thread 1: Fatal error: failed to find a currently active container for Task

The debugger is highlighting this line in the call stack (not sure if that's useful as a newbie):

#7	0x0000000100bb6d90 in Task.init(id:title:priority:) at /var/folders/3v/q8g4z9bx4lb9z6t7mhgwgghw0000gn/T/swift-generated-sources/@__swiftmacro_10BadgerTool4Task5ModelfMm_.swift:2

Here's the code:

The Task model isn't complex:

//  Task.swift
import Foundation
import SwiftData

@Model
class Task {
    @Attribute(.unique) var id: UUID
    var title: String
    var priority: String
    
    init(id: UUID = UUID(), title: String, priority: String = "None") {
        self.id = id
        self.title = title
        self.priority = priority
    }
}

I have the model container set in the context of the highest view:

//  BadgerToolApp.swift
import SwiftUI
import SwiftData

@main
struct BadgerToolApp: App {
    var body: some Scene {
        WindowGroup {
            NavView()
            .modelContainer(for: Task.self)
        }
    }
}

I tried moving all other views one layer down (which is why the unnecessary NavView is there):

//  NavView.swift
import SwiftUI
import SwiftData

struct NavView: View {
    @State var selectedCollection: Collection?
    @State var selectedTask: Task?
    
    var body: some View {
        NavigationSplitView(
            sidebar: {
                SideBarView(selectedCollection: $selectedCollection, selectedTask: $selectedTask)
            },
            content: {
                ContentListView(selectedCollection: $selectedCollection, selectedTask: $selectedTask)
            },
            detail: {
                TaskDetailView(selectedCollection: $selectedCollection, selectedTask: $selectedTask)
            }
        )
    }
}

Trying to isolate my mistake

I removed everything else related to SwiftData (except for the imports) and gave my views hard-coded data for the simulator like this:

//  SideBarView.swift
import SwiftUI
import SwiftData

struct SideBarView: View {
    @Binding var selectedCollection: Collection?
    @Binding var selectedTask: Task?
    let collections = presetCollections //temp data

    var body: some View {
            List(collections, id: \.id, selection: $selectedCollection){ collection in
                NavigationLink(collection.name, value: collection)
            }
            List{
                Text("All Tasks")
                Text("Settings")
            }
            .navigationTitle("Collections")
    }

}

Everything works as expected if

• I comment out the .modelContainer() modifier on the call to NavView view
• I change the Task definition from the @Model class to a regular struct like this:

//  Task.swift
// with @Model removed

import Foundation

struct Task: Hashable {
    var id: UUID
    var title: String
    var priority: String
    
    init(id: UUID = UUID(), title: String, priority: String = "None") {
        self.id = id
        self.title = title
        self.priority = priority
    }
}

What am I missing? Could it be a bug?

Thanks for your help!