Xcode 15 beta 4 not building without clear indication [because of @Observable class]

I had this Xcode 15 beta 4 failing to build on a SwiftUI project. There was no clear indication on the cause of the failure. The build log hinted at a compiler errors with a file hosting an @Observable class.

This class have some properties that have function types.

To fix the issue, I made them "@ObservationIgnored" as they were not "@Published" when still under conformance with "@ObservableObject".

The source code fixed:

@available(iOS 17, *)
@Observable
final class LiveSprints: LiveRecords {
    
    typealias Entity = Sprint
    typealias Store = DBStore
    
    @ObservationIgnored
    var filtering: (Sprint) -> Bool = { _ in true }
    
    @ObservationIgnored
    var ordering: (Sprint, Sprint) -> Bool = { _, _ in true }

    var masterID: UUID? = nil
    
    @ObservationIgnored
    var observer: MultiObserver<DB>? = nil
    
    var records: [Hierarchized<Sprint>] = []
    
}