Object reference not set to an instance of an object

NullReferenceException: Object reference not set to an instance of an object Indingo_Lava_Burst_Glitch_Fixed.Start () (at Assets/Scripts/Indingo_Lava_Burst_Glitch_Fixed.cs:18)

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Indingo_Lava_Burst_Glitch_Fixed : MonoBehaviour {
 
     private Indingo_Lava_Burst_Collider_Detecter_Attach_On_Enemies disableLavaBurst01;
 
     private Indingo_Lava_Burst_Activator_Deactivator_Attach_On_Indingo disableLavaBurst02;
 
     // Use this for initialization
     void Start () {
 
         disableLavaBurst01 = GetComponent<Indingo_Lava_Burst_Collider_Detecter_Attach_On_Enemies>();
 
         disableLavaBurst02 = GetComponent<Indingo_Lava_Burst_Activator_Deactivator_Attach_On_Indingo>();
 
         disableLavaBurst01.enabled = false;
         disableLavaBurst02.enabled = false;
 
     }
 
     // Update is called once per frame
     void FixedUpdate () {
 
 
     }
 
     void OnCollisionEnter2D(Collision2D coll) {
         if (coll.gameObject.tag == "Enemy")
         {
             disableLavaBurst01.enabled = true;
             disableLavaBurst02.enabled = true;
             Debug.Log ("Indingo Collided With Enemy");
         }
         else
         {
             disableLavaBurst01.enabled = false;
             disableLavaBurst02.enabled = false;
             Debug.Log ("Indingo Did Not Collided With Enemy");
         }
     }
 }