I NEED HELP! calling a function from another script but deleting it afterwards!

hello i am new to unity and this fourm so if you undesrtand my problem please explain it to me as simple as possible

problem is in line 70 in motion script and 77

when i instantiate the object everything works fine but if i dont instantiate the object it gives me error since it can not find the refrence for the script
can you tell me how to fix this and explain it to me as simple as possible for some one with low iq


motion script!

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Motion : MonoBehaviour
6. {
7.     public float speed;
8.     private Rigidbody rig;
9.     public float sprintmodifire;
10.     public Camera PlayerCam;
11.  
12.     public Transform groundchek;
13.     public LayerMask groundmask;
14.     private float t_adjustedSpeed;
15.  
16.     public float jumpforce;
17.     private float BaseFOV;
18.     private float FOVmodifre = 1.2f;
19.     void Start()
20.     {
21.         rig = GetComponent<Rigidbody>();
22.         BaseFOV = PlayerCam.fieldOfView;
23.     }
24.  
25.     public IEnumerator GrapplePush()
26.     {
27.         rig.AddRelativeForce((Vector3.forward * t_adjustedSpeed / 7));
28.         yield return new WaitForSeconds(1f);
29.         FindObjectOfType<GrapplingGunScript>().isGrapling = false;
30.  
31.     }
32.  
33.     // Update is called once per frame
34.     void FixedUpdate()
35.     {
36.         bool isGorunded;
37.         isGorunded = Physics.Raycast(groundchek.position, Vector3.down, 0.1f, groundmask);
38.         //Axis and motion
39.         float t_Hmove = Input.GetAxis("Horizontal");
40.         float t_Vmove = Input.GetAxis("Vertical");
41.         //we save them both in a vector 3
42.         Vector3 t_direction = new Vector3(  t_Hmove,0, t_Vmove);
43.         // when we press w and d at same time we add 1from w on 1 from d so it makes player go faster so we nomlize (keep it 1)
44.         t_direction.Normalize();
45.      
46.         //Controls
47.         bool spirnt = Input.GetKey(KeyCode.LeftShift);
48.         bool jump = Input.GetKey(KeyCode.Space);
49.  
50.         //motion and sprint and camera lerping
51.  
52.         bool isjumping = jump;
53.         bool isSprinting = spirnt && t_Vmove >0 && !isjumping && isGorunded;
54.  
55.         if (isjumping && isGorunded )
56.         {
57.             rig.AddForce( Vector3.up * jumpforce);
58.         }
59.          t_adjustedSpeed = speed;
60.      
61.  
62.  
63.      
64.  
65.  
66.         if (isSprinting)
67.         {
68.             t_adjustedSpeed = sprintmodifire * t_adjustedSpeed;
69.         }
70.         if (!FindObjectOfType<GrapplingGunScript>().isGrapling || )
71.         {
72.             Vector3 TargetVelocity = transform.TransformDirection(t_direction) * t_adjustedSpeed * Time.deltaTime;
73.             TargetVelocity.y = rig.velocity.y;
74.             rig.velocity = TargetVelocity;
75.             print("first work");
76.         }
77.         else if(FindObjectOfType<GrapplingGunScript>().isGrapling)
78.         {
79.  
80.             StartCoroutine(GrapplePush());
81.          
82.             print("secounds work");
83.         }
84.      
85.      
86.         if (isSprinting)
87.         {
88.             PlayerCam.fieldOfView = Mathf.Lerp(PlayerCam.fieldOfView,BaseFOV *FOVmodifre,Time.deltaTime*8f);
89.         }
90.         else
91.         {
92.             PlayerCam.fieldOfView = Mathf.Lerp(PlayerCam.fieldOfView, BaseFOV , Time.deltaTime * 8f);
93.         }
94.  
95.      
96.      
97.     }
98.  
99.  
100. }
101.  

grapple gun script!

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class GrapplingGunScript : MonoBehaviour
6. {
7.     private LineRenderer Lr;
8.     private Vector3 GrapplePoint;
9.     public LayerMask Graprable;
10.     public Transform GunTip;
11.     private float MaxDistance =100f;
12.     private SpringJoint Joints;
13.     public bool isGrapling = false;
14.  
15.  
16.     private void Awake()
17.     {
18.         Lr = GetComponent<LineRenderer>();
19.     }
20.  
21.     private void Update()
22.     {
23.         //rather than use (public transfrom) we used this becuse in a prefab we can not refrence them when we instaciate
24.         //so we refrence them using tags
25.         var cam = GameObject.FindWithTag("Cam");
26.         var Player = GameObject.FindWithTag("Player");
27.  
28.  
29.         if (Input.GetMouseButtonDown(0))
30.         {
31.             StartGrapple();
32.          
33.          
34.         }else if (Input.GetMouseButtonUp(0))
35.         {
36.  
37.         }
38.         void StartGrapple()
39.         {
40.             RaycastHit Hit;
41.             isGrapling = true;
42.             if (Physics.Raycast(origin: cam.transform.position,direction: cam.transform.forward,out Hit,MaxDistance,Graprable))
43.             {
44.                 GrapplePoint = Hit.point;
45.                 Joints = Player.gameObject.AddComponent<SpringJoint>();
46.                 Joints.autoConfigureConnectedAnchor = false;
47.                 Joints.connectedAnchor = GrapplePoint;
48.  
49.                 float DistanceFromPoint = Vector3.Distance(a: Player.transform.position, b: GrapplePoint);
50.  
51.                 //distance it will try to keep you from grappling
52.                 Joints.maxDistance = DistanceFromPoint * 0.8f;
53.                 Joints.minDistance = DistanceFromPoint * 0.25f;
54.  
55.                 //change values how you see fit
56.                 Joints.spring = 4.5f;
57.                 Joints.damper = 7f;
58.                 Joints.massScale = 4.5f;
59.             }
60.         }
61.     }
62.     private void LateUpdate()
63.     {
64.         DrawRope();
65.     }
66.     void DrawRope()
67.     {
68.         Lr.SetPosition(index: 0, GunTip.position);
69.         Lr.SetPosition(index: 1, GrapplePoint);
70.     }
71. }
72.  

 

You need to do a null check. For example:

Code (csharp):

1. var grappler = FindObjectOfType<GrapplingGunScript>();
2. if (grappler != null && grappler.isGrapling) {

There's also a shortcut called the "null coalescing" operator. Basically it means, "If this thing is null, return fallse, if it's not null, keep digging". It's the question mark in the following example:

Code (csharp):

1. if (FindObjectOfType<GrapplingGunScript>()?.isGrapling) {

 

THANK YOU
i thought about it being something to do with null thingy but i did not know how to use it properly XD
thanks