Help NullReferenceException in ObiRopeCursor (build)

Code:
using System.Collections.Generic;

using UnityEngine;

using CI.QuickSave;

using UnityEngine.UI;

using UnityEngine.SceneManagement;

using Obi;



public class SaveLoadManager : MonoBehaviour

{



    public InputField inputField;

    public ObiActor actor;

    public ObiRope tether;

    public ObiRopeCursor cursor;

    public List<GameObject> ObjectsToSave;

    public GameObject TMS_ROV;

    QuickSaveWriter writer;

    QuickSaveReader reader;

    SettingsManager sm;



    void Start()

    {

        var settings = GameObject.Find("Settings");

        sm = settings.GetComponent<SettingsManager>();



        if (sm.saveFile != "")

        {

            Load(sm.saveFile);

        }

        sm.scenarioLoaded = true;

    }



    public void Save()

    {

        if (inputField.text == "") return;

        writer = QuickSaveWriter.Create($"{SceneManager.GetActiveScene().name} - {inputField.text}");

        int idx = 1;

        foreach (var obj in ObjectsToSave)

        {

            writer.Write($"{idx}_{obj.name}_position", obj.transform.position);

            writer.Write($"{idx}_{obj.name}_rotation", obj.transform.rotation);

            idx++;



            if (obj.name == "TMS")

            {

                var ctrl = obj.GetComponent<HcuTmsController>();

                writer.Write("latched", ctrl.latched);

                writer.Write("latch_button", ctrl.latchedButton);

            }



            if (obj.name == "a-frame_edit")

            {

                var ctrl = obj.GetComponent<UmbilicalController>();

                writer.Write("frame_angle", ctrl.angle);

            }

            if (obj.name == "BULLET")

            {

                writer.Write("bullet_minAngle", obj.GetComponent<HingeJoint>().limits.min);

                writer.Write("bullet_maxAngle", obj.GetComponent<HingeJoint>().limits.max);

                continue;

            }

        }

        List<Vector3> positions = new();

        List<Vector3> velocities = new();

        for (int i = 0; i < actor.solverIndices.Length; ++i)

        {

            int solverIndex = actor.solverIndices[i];



            positions.Add(actor.solver.positions[solverIndex]);

            velocities.Add(actor.solver.velocities[solverIndex]);

        }

        writer.Write("tether_positions", positions);

        writer.Write("tether_velocities", velocities);

        writer.Write("tether_length", tether.restLength);



        writer.Commit();

        Debug.Log("Save complete!");



    }



    public void Load(string saveFile="test")

    {

        HcuTmsController ctrl = null;



        reader = QuickSaveReader.Create(saveFile);

        int idx = 0;

        foreach (var obj in ObjectsToSave)

        {

            idx++;



            if (obj.name == "TMS")

            {

                ctrl = obj.GetComponent<HcuTmsController>();

                ctrl.latched = reader.Read<bool>("latched");

                ctrl.latchedButton = reader.Read<bool>("latch_button");

            }





            if (obj.name == "a-frame_edit")

            {

                obj.transform.position = reader.Read<Vector3>($"{idx}_{obj.name}_position");

                obj.transform.rotation = reader.Read<Quaternion>($"{idx}_{obj.name}_rotation");

                var ctrl2 = obj.GetComponent<UmbilicalController>();

                ctrl2.Init();

                ctrl2.startAngle = reader.Read<Quaternion>($"{idx}_{obj.name}_rotation").eulerAngles.x;

                ctrl2.Rotate();

                continue;

            }

            if (obj.name == "BULLET")

            {

                continue;

            }



            obj.transform.position = reader.Read<Vector3>($"{idx}_{obj.name}_position");

            obj.transform.rotation = reader.Read<Quaternion>($"{idx}_{obj.name}_rotation");

        }



        // rope loading

        var positions = reader.Read<List<Vector3>>("tether_positions");

        var velocities = reader.Read<List<Vector3>>("tether_velocities");

        for (int i = 0; i < positions.Count; ++i)

        {

            int solverIndex = actor.solverIndices[i];

            actor.solver.positions[solverIndex] = positions[i];

            actor.solver.velocities[solverIndex] = velocities[i];

        }

        cursor.ChangeLength(reader.Read<float>("tether_length"));



        Debug.Log("Load complete!");

    }

}