Exception when setting an optional binding to nil in SwiftUI after checking

Here is a possible approach to fix this. Tested with Xcode 12 / iOS 14.

The-Variant! - Don't use optional state/binding & force-unwrap ever :)

Variant1: Use binding wrapper (no other changes)

CRTestView(optional: Binding(
        get: { self.optional ?? -1 }, set: {self.optional = $0}
    ))

Variant2: Transfer binding as-is

struct ContentView: View {
    @State var optional: Int?

    var body: some View {
        VStack {
            if optional == nil {
                Text("Nil")
            } else {
                CRTestView(optional: $optional)
            }

            Button(action: {
                if optional == nil {
                    optional = 0
                } else {
                    optional = nil
                }
            }) {
                Text("Toggle")
            }
        }
    }
}

struct CRTestView: View {
    @Binding var optional: Int?

    var body: some View {
        VStack {
            Text(optional?.description ?? "-1")

            Button(action: {
                optional? += 1
            }) {
                Text("Increment")
            }
        }
    }
}