我正在尝试制作一个系统，用户可以使用空格键逐渐将车辆转向90度，并且在按住空格键时车辆保持完全转向，但在输入停止时车辆逐渐返回0度旋转。
当我把一个逐渐上升和下降的定时器变量放入Lerp函数时，它只会给出错误：表达式Assert失败：'!比较近似值（标量，0.0F）'

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Movement : MonoBehaviour
{
    private static float turnTimer = 2f;
    private float turnTimeElapsed;
    private float clampedTimeElapsed;
    private float lerpTimer;

    [SerializeField] private float turnSpeed;

    Quaternion endRot;

    Rigidbody ridgy;

    private void Start()
    {
        ridgy = this.GetComponent<Rigidbody>();

        turnTimeElapsed = 0f;

        Quaternion endRot = Quaternion.Euler(0f, 90f, 0f);
    }

    private void Update()
    {
        if (Input.GetKey(KeyCode.Space) && turnTimeElapsed < turnTimer)
        {
            turnTimeElapsed += turnSpeed * Time.deltaTime;
            
        }
        else if (!Input.GetKey(KeyCode.Space) && turnTimeElapsed > 0)
        {
            turnTimeElapsed -= turnSpeed * Time.deltaTime;
        }

        clampedTimeElapsed = Mathf.Clamp(turnTimeElapsed, 0f, turnTimer);

        lerpTimer = clampedTimeElapsed / turnTimer;

        transform.rotation = Quaternion.Lerp(Quaternion.identity, endRot, lerpTimer);
    }
}