Indexoutofrangeexception: index was outside the bounds of array -- unity

//Variables
    private List<AnswerData> PickedAnswers = new List<AnswerData>();
    private List<int> FinishedQuestions = new List<int>();
    private int currentQuestion = 0;

//Methods
   Question GetRandomQuestion()
   {
       var randomIndex = GetRandomQuestionIndex();
       currentQuestion = randomIndex;

       return data.Questions[currentQuestion];
   }
   int GetRandomQuestionIndex()
   {
       var random = 0;


       if (FinishedQuestions.Count < data.Questions.Length)
       {
           do
           {
               random = UnityEngine.Random.Range(0, data.Questions.Length);
           } while (FinishedQuestions.Contains(random) || random == currentQuestion);
       }
       return random;

//Data Class

[System.Serializable()]
public class Data
{
    public Question[] Questions = new Question[0];

    public Data(){}

    public static void Write(Data data, string path)
    {
        XmlSerializer serializer = new XmlSerializer(typeof(Data));
        using (Stream stream = new FileStream(path,FileMode.Create))
        {
            serializer.Serialize(stream, data);
        }
    }
    public static Data Fetch(string filePath)
    {
        return Fetch(out bool result,filePath);
    }
    public static Data Fetch(out bool result, string filePath)
    {
        if (File.Exists(filePath)) 
        {
            result = false;
            return new Data();
        }
        XmlSerializer deserializer = new XmlSerializer(typeof(Data));
        using (Stream stream = new FileStream(filePath, FileMode.Open))
        {
            var data = (Data)deserializer.Deserialize(stream);

            result = true;
            return data;
        }
    }
}