问什么是"System.ArgumentOutOfRangeException：‘索引超出范围。必须是非负数并且小于集合的大小“？

EN

    public static void Main(string[] args)
    {
        Console.Write("Enter a few numbers (eg 1-2-3-4): ");

        var input = Console.ReadLine();
        var numArray = new List<int>();

        foreach (var number in input.Split('-'))
        {
            numArray.Add(Convert.ToInt32(number));
        }
        numArray.Sort();

        var isConsecutive = true;
        for (int i = 0; i < numArray.Count; i++)
        {
            if (numArray[i] != numArray[i + 1] - 1)
            {
                isConsecutive = false;
                break;
            }
        }

        if (isConsecutive)
        {
            Console.WriteLine("Consecutive");
            Console.ReadLine();
        }
        else
        {
            Console.WriteLine("Not Consecutive");
            Console.ReadLine();
        }
    }