I want to preview my file but can’t because of this error: Type of expression is ambiguous without a type annotation. im using Xcode beta 16 and target iOS 18

import SwiftUI

struct WorkoutStartView: View {
    @Binding var workout: Workout?
    
    var body: some View {
        VStack {
           // my code
    }
}


#Preview {
    let sampleExercises: [Exercise] = [
        Exercise(name: "Sit-ups", imageName: "sitUps", difficulty: 3, guidelines: "Test guidelines for crunches.", muscle: "Upper"),
        
        Exercise(name: "Leg raises", imageName: "legRaises", difficulty: 3, guidelines: "Test guidelines for reverse crunches.", muscle: "Lower"),
        
        Exercise(name: "L-sit", imageName: "lSit", difficulty: 3, guidelines: "Test guidelines for flutter kicks.", muscle: "6 Pack"),
        
        Exercise(name: "Side jack-knives", imageName: "sideJackKnives", difficulty: 3, guidelines: "Test guidelines for sitting twists.", muscle: "Obliques"),
        
        Exercise(name: "Dead bug", imageName: "deadBug", difficulty: 3, guidelines: "Test guidelines for knee to elbow.", muscle: "Complete"),
        
        Exercise(name: "Wipers", imageName: "wipers", difficulty: 3, guidelines: "Test guidelines for half wipers.", muscle: "Core"),
        
        Exercise(name: "Long arm cruches", imageName: "longArmCrunches", difficulty: 4, guidelines: "Test guidelines for crunches.", muscle: "Upper"),
        
        Exercise(name: "Pulse ups", imageName: "pulseUps", difficulty: 4, guidelines: "Test guidelines for reverse crunches.", muscle: "Lower"),
        
        Exercise(name: "Star plank", imageName: "starPlank", difficulty: 4, guidelines: "Test guidelines for flutter kicks.", muscle: "6 Pack")
    ]
    
    @State var sampleWorkout: Workout? = Workout(
    name: "Morning Routine",
    difficulty: 3,
    workingTime: 30,
    recoveryTime: 30,
    isSet: false,
    duration: 8
    )
    
    sampleWorkout!.exercises = sampleExercises
    WorkoutStartView(workout: $sampleWorkout).preferredColorScheme(.dark)
}

sorry for the bigs code blocks but wanted my error to be reproducible.
here are the two classes implied implementation:

@Model
class Workout: Identifiable {
    var id: UUID
    var name: String
    var difficulty: Int
    var workingTime: Int
    var recoveryTime: Int
    var count: Int
    var duration: Int
    var isSet: Bool
    var setNumber: Int?
    var restTime: Int?
    
    // Define a one-to-many relationship with Exercise
    @Relationship(deleteRule: .cascade, inverse: Exercise.workout) var exercises: [Exercise]? = [Exercise]()
    
    init(name: String, difficulty: Int, workingTime: Int, recoveryTime: Int, isSet: Bool, duration: Int, setNumber: Int? = nil, restTime: Int? = nil) {
        self.id = UUID()
        self.name = name
        self.difficulty = difficulty
        self.count = 0
        self.duration = duration
        self.workingTime = workingTime
        self.recoveryTime = recoveryTime
        self.isSet = isSet
        self.setNumber = setNumber
        self.restTime = restTime
    }
    
    func difficultySymbol() -> Image {
        switch difficulty {
        case 1:
            return Image(systemName: "circle.fill")
        case 2:
            return Image(systemName: "triangle.fill")
        case 3:
            return Image(systemName: "square.fill")
        case 4:
            return Image(systemName: "hexagon.fill")
        case 5:
            return Image(systemName: "star.fill")
        default:
            return Image(systemName: "flame.fill")
        }
    }
    
    func ToString() -> String {
        var res = "(name) - (difficultySymbol()) - (workingTime)n"
        for exercise in exercises! {
            res += "t(exercise.name)n"
        }
        return res
    }
}

@Model
class Exercise: Identifiable, Equatable {
    var id: UUID
    var name: String
    var imageName: String
    var difficulty: Int
    var guidelines: String
    var muscle: String
    
    // Define the relationship back to Workout
    var workout: Workout?

    init(name: String, imageName: String, difficulty: Int, guidelines: String, muscle: String, workout: Workout? = nil) {
        self.id = UUID()
        self.name = name
        self.imageName = imageName
        self.difficulty = difficulty
        self.guidelines = guidelines
        self.muscle = muscle
        self.workout = workout
    }
    
    static func == (lhs: Exercise, rhs: Exercise) -> Bool {
        return lhs.name == rhs.name
    }
    
    func hash(into hasher: inout Hasher) {
            hasher.combine(name)
        }
    
    var image: Image {
        Image(imageName)
    }
    
    var muscleImg: Image {
        Image(muscle)
    }
    
    func difficultySymbol() -> Image {
        switch difficulty {
        case 1:
            return Image(systemName: "circle.fill")
        case 2:
            return Image(systemName: "triangle.fill")
        case 3:
            return Image(systemName: "square.fill")
        case 4:
            return Image(systemName: "hexagon.fill")
        case 5:
            return Image(systemName: "star.fill")
        default:
            return Image(systemName: "flame.fill")
        }
    }
    
    func toString() -> String {
        return "(name) - (muscle) - (difficulty)"
    }
}

Of course, I tried to type annotate all my variable but nothing fixed.

I waited too much code so I have to write more to post this code. ignore this please.