Drawing lines from mouse position

Tested and updated to fix errors

 using System.Collections.Generic;
 using UnityEngine;
 
 [RequireComponent(typeof(LineRenderer))]
 public class LineRendererTest : MonoBehaviour
 {
     List<Vector3> linePoints = new List<Vector3>();
     LineRenderer lineRenderer;
     public float startWidth = 1.0f;
     public float endWidth = 1.0f;
     public float threshold = 0.001f;
     Camera thisCamera;
     int lineCount = 0;
 
     Vector3 lastPos = Vector3.one * float.MaxValue;
     
     
     void Awake()
     {
         thisCamera = Camera.main;
         lineRenderer = GetComponent<LineRenderer>();
     }
 
     void Update()
     {
         Vector3 mousePos = Input.mousePosition;
         mousePos.z = thisCamera.nearClipPlane;
         Vector3 mouseWorld = thisCamera.ScreenToWorldPoint(mousePos);
         
         float dist = Vector3.Distance(lastPos, mouseWorld);

         if(dist <= threshold)
             return;
         
         lastPos = mouseWorld;
         if(linePoints == null)
             linePoints = new List<Vector3>();
         linePoints.Add(mouseWorld);
         
         UpdateLine();
     }
 
 
     void UpdateLine()
     {
         lineRenderer.SetWidth(startWidth, endWidth);
         lineRenderer.SetVertexCount(linePoints.Count);
 
         for(int i = lineCount; i < linePoints.Count; i++)
         {
             lineRenderer.SetPosition(i, linePoints[i]);
         }
         lineCount = linePoints.Count;
     }
 }