Erro no Camera.main

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

public class movimentar : MonoBehaviour{ public float Velocidade = 10; Vector3 direcao ; public LayerMask chao;

// Update is called once per frame
void Update(){
    float eixoX = Input.GetAxis("Horizontal");
    float eixoZ = Input.GetAxis("Vertical");

    direcao = new Vector3(eixoX,0,eixoZ);

    if(direcao != Vector3.zero){
        GetComponent<Animator>().SetBool("Mover",true);
    }else{
        GetComponent<Animator>().SetBool("Mover",false);
    }

}
void FixedUpdate(){
    GetComponent<Rigidbody>().MovePosition
    (GetComponent<Rigidbody>().position +(direcao * Velocidade * Time.deltaTime));

    Ray raio = Camera.main.ScreenPointToRay(Input.mousePosition);
    Debug.DrawRay(raio.origin,raio.direction * 100,Color.red);

    RaycastHit impacto;

    if(Physics.Raycast(raio, out impacto, 100)){
        Vector3 posicaoJogador = impacto.point - transform.position;

        posicaoJogador.y = transform.position.y;

        Quaternion novaRotacao = Quaternion.LookRotation(posicaoJogador);
        GetComponent<Rigidbody>().MoveRotation(novaRotacao);
    }
}

}