How to create a new instance of an object?

I am trying to create a node system which is aware of its neighbours with an edge class. The code below is creating an error of NullReferenceExeption: Object reference not set to an instance of an object NodeScript.GenerateEdges() (at Assets/Scripts/NodeScript.cs:109).

 public void GenerateEdges()
     {
         Collider[] neighbourNodes = Physics.OverlapBox(transform.position, transform.localScale);
 
         int edgeNumber = 0;
         foreach(Collider nodeCollider in neighbourNodes)
         {
             NodeScript node = nodeCollider.gameObject.GetComponent<NodeScript>();
 
             if(node != null)
             {
                 EdgeScript edge = new EdgeScript();
                 
                 edge.SetFrom(this);
                 edge.SetTo(node);
                 edge.SetCost((node.transform.position - this.transform.position).magnitude);
 
                 edges.Add(edge); // <-- Error is on this line
                 ++edgeNumber;
             }
         }
     }

Here is the EdgeScript class as well:

 public class EdgeScript {

 private NodeScript from;
 private NodeScript to;
 private float cost;

 public EdgeScript()
 {

 }

 ~EdgeScript()
 {

 }

 public void SetFrom(NodeScript newFrom)
 {
     if (newFrom != null)
     {
         from = newFrom;
     }
 }

 public void SetTo(NodeScript newTo)
 {
     if (newTo != null)
     {
         to = newTo;
     }
 }

 public void SetCost(float newCost)
 {
     cost = newCost;
 }}

What have I done wrong?

P.S. I realise I need Get functions in the EdgeScript I haven't finished the class yet.