fix: don't use removable Section header in NavigationSplit

[eagleoflqj]

Async operations on view model doesn't eliminate the bug. It only makes it intermittent.
Minimal reproducible view on macOS:

import SwiftUI

struct HeaderView: View {
  let onDelete: () -> Void

  var body: some View {
    Text("Header")
      .contextMenu {
        Button {
          onDelete()
        } label: {
          Text("Delete")
        }
      }
  }
}

struct ContentView: View {
  @State private var list = [String]()

  var body: some View {
    NavigationSplitView {
      List {
        ForEach(list, id: \.self) { item in
          Section(header: HeaderView(onDelete: {
            list.removeAll { $0 == item }
          })) {
            Text(item)
          }
        }
      }
    } detail: {
      Text("Detail")
    }.onAppear() {
      list = ["Item 1", "Item 2", "Item 3"]
    }
  }
}

Without NavigationSplit or without header the crash won't happen. Absolutely a bug in SwiftUI.

[github-actions]

arm64 comparison

No difference.

x86_64 comparison

No difference.