函數 remove(atOffsets:) 只在運行時抱怨錯誤類型

我在 Playground 中有這個非常簡單的代碼。它編譯時沒有錯誤，但是當我嘗試運行它時，出現remove(atOffsets:)函數錯誤。這是為什麼？

enum CandyColor: CaseIterable {
    case red, green, yellow, brown
}
enum CandyFilling: CaseIterable {
    case chocolade, nuts
}

extension CaseIterable {
    static var random: Self {
        Self.allCases.randomElement()!
    }
}

typealias Candy = (color: CandyColor, filling: CandyFilling)

var candies = (0...20).map{ _ in Candy(color: CandyColor.random, filling: CandyFilling.random)}

var redWithChocolade = [Candy]()
var yellowWithNuts = [Candy]()
var brownAndGreenWithChocolade = [Candy]()

var indiciesToRemove = IndexSet()
for (index, candy) in candies.enumerated() {
    switch candy {
    case (.red, .chocolade):
        redWithChocolade.append(candy)
        indiciesToRemove.insert(index)
    case (.yellow, .nuts):
        yellowWithNuts.append(candy)
        indiciesToRemove.insert(index)
    case let(c) where [.brown, .green].contains(c.color) && c.filling == .chocolade:
        brownAndGreenWithChocolade.append(c)
        indiciesToRemove.insert(index)
    default:
        break
    }
}

candies.remove(atOffsets: indiciesToRemove) // Error: candidate expects value of type 'Int' for parameter #1

print("Left in heap: \(candies)")