Result of call to 'onReceive(_:perform:)' is unused

Using Swift
1

The call to input is unused, I see some people use an _ but I get the same error. thank you for any guidance.

Text("Distance: \(self.travelDistance)").modifier(MainMenuModifier(trimColor: .green))
                    .onReceive(self.timer) { input in
                        self.latitude2 = location.coordinate.latitude
                        self.longitude2 = location.coordinate.longitude
                        self.travelDistance = self.calculateDistance(lat1: self.latitude1, lon1: self.longitude1, lat2: self.latitude2, lon2: self.longitude2)
                    print("travel distance: \(self.travelDistance)")
                }