Where did NullReferenceExeption come from?

Question

Unity

using UnityEngine;
using System.Collections;

public class PlayerMovement : MonoBehaviour {

    public float Speed = 6f;

    Vector3 _movement;
    Animator _anim;
    Rigidbody _playerRigidBody;
    int _floorMask;
    float CamRayLength = 100f;
    void Start()
    {
        _floorMask = LayerMask.GetMask("Floor");
        _anim = GetComponent<Animator>();
        _playerRigidBody = GetComponent<Rigidbody>();
    }
    void FixedUpdate()
    {
        float h = Input.GetAxisRaw("Horizontal");
        float v = Input.GetAxisRaw("Vertical");
        Move(h, v);
        Turning();
    }
    void Move(float h, float v)
    {
        _movement.Set(h, 0f, v);
        _movement = _movement.normalized * Speed * Time.deltaTime;
        _playerRigidBody.MovePosition(transform.position + _movement);
    }
    void Turning()
    {
        Ray camRay = Camera.main.ScreenPointToRay(Input.mousePosition);
        RaycastHit floorHit;
        if (Physics.Raycast(camRay, out floorHit, CamRayLength, _floorMask))
        {

            Vector3 playerToMouse = floorHit.point - transform.position;
            playerToMouse.y = 0;
            Quaternion newRotation = Quaternion.LookRotation(playerToMouse);
            _playerRigidBody.MoveRotation(newRotation);
        }

    }
  // Update is called once per frame
  void Update () {
  
  }
}

And here is the error itself:
NullReferenceException: (null)
UnityEditor.SerializedObject..ctor (UnityEngine.Object[] objs) (at C:/buildslave/unity/build/artifacts/generated/common/editor/SerializedPropertyBindings.gen.cs:74 )
UnityEditor.AssetImporterInspector.GetSerializedObjectInternal () (at C:/buildslave/unity/build/Editor/Mono/ImportSettings/AssetImporterInspector.cs:57)
UnityEditor.Editor.get_serializedObject () (at C:/buildslave/unity/build/artifacts /generated/common/editor/EditorBindings.gen.cs:147)
UnityEditor.ModelImporterClipEditor.OnEnable () (at C:/buildslave/unity/build/Editor/Mono/ImportSettings/ModelImporterClipEditor.cs:139)
The code is completely working, doing all its functions, and all the necessary objects are present on the player
Or is the error related to the imported player model?

Answer 1

The next day, the error disappeared as unexpectedly as it appeared)