LineRenderer (strange bug)

Hello, I have a pretty weird problem with the LineRenderer component: I want to join each WayPoint (capsule) of my scene with LineRenderer in a progressive way. I managed to do it with the code below but each time it touches a WayPoint (capsule), a line is created to the point 0,0,0 for 1 frame before disappearing. I do not understand ... my code is correct and does not mention doing that.

my assumption is that it comes when I increment its size '' lineRenderer.positionCount ++ "which makes me create a time 0,0,0 before the position changes.

Do you have an idea to avoid this temporary line please? Here is my code that I commented the 5/6 lines of code concerned by the LineRenderer with '' // here '':

     LineRenderer lineRenderer;
     private int indexLine = 0;
     public float linearSpeed = 5;

     private void Start()
     {
         lineRenderer = gameObject.GetComponent<LineRenderer>();  //here
         lineRenderer.positionCount = 1;  //here
         lineRenderer.SetPosition(0, start.transform.position);  //here
         NavigateTo(start, end);
     }
     
     void Update()
     {
         if (currentPath != null && currentPath.Count > 0) 
         {
             if (moveTimeCurrent < moveTimeTotal)
             {
                 moveTimeCurrent += Time.deltaTime;
                 if (moveTimeCurrent > moveTimeTotal)
                     moveTimeCurrent = moveTimeTotal;
                 var pointALongLine = Vector3.Lerp (currentWaypointPosition, currentPath.Peek(), moveTimeCurrent / moveTimeTotal);  //here
                 lineRenderer.SetPosition(indexLine, pointALongLine);  //here
             } else
             {
                 currentWaypointPosition = currentPath.Pop(); 
                 if (currentPath.Count == 0)
                     Stop ();
                 else
                 {
                     lineRenderer.positionCount++; //here
                     indexLine = indexLine + 1; //here
                     moveTimeCurrent = 0;
                     moveTimeTotal = (currentWaypointPosition - currentPath.Peek()).magnitude / linearSpeed;
                 }