我试图在Unity中使文本淡入淡出，但我的for循环中的代码返回一个NullReferenceException

using UnityEngine;
using UnityEngine.UI;

public class TextFade : MonoBehaviour
{
    public Text text;
    public float fadeDuration = 1f;

    private void Start()
    {
        StartCoroutine(FadeText());
    }

    private System.Collections.IEnumerator FadeText()
    {
        Color originalColor = text.color;
        Color transparentColor = new Color(originalColor.r, originalColor.g, originalColor.b, 0f);

        float elapsedTime = 0f;
        while (elapsedTime < fadeDuration)
        {
            float alpha = Mathf.Lerp(1f, 0f, elapsedTime / fadeDuration);
            text.color = Color.Lerp(originalColor, transparentColor, alpha);
            elapsedTime += Time.deltaTime;
            yield return null;
        }

        // 确保文本完全淡出
        text.color = transparentColor;
    }
}