How to fix error CS0029: Cannot implicitly convert type `SpaceShooter_GameController' to `UnityEngine.GameObject'

Hi, I don't know how to fix this error. The problem text is in bold. Below the script code with the problem is the script that I believe the problem is trying to link to / reference...

Problem Script:

 using UnityEngine;
 using System.Collections;
 
 public class SpaceShooter_DestoryByContact_Asteroid : MonoBehaviour 
 {
     public GameObject explosion;
     public GameObject playerExplosion;
     public int scoreValue;
     public SpaceShooter_GameController gameController;
 
     void Start ()
     {
         GameObject gameControllerObject = GameObject.FindWithTag ("GameController");
         if (gameControllerObject != null) 
         {
             **gameControllerObject = gameControllerObject.GetComponent <SpaceShooter_GameController> ();**
         }
         if (gameController == null) 
         {
             Debug.Log ("Cannot find 'SpaceShooter_GameController' script");
         }
     }
 
     void OnTriggerEnter (Collider other) 
     {
         if (other.tag == "Boundary_SpaceShooter") 
         {
             return;
         }
         Instantiate(explosion, transform.position, transform.rotation);
         if (other.tag == "Player") {
             Instantiate (playerExplosion, other.transform.position, other.transform.rotation);
         }
         gameController.AddScore (scoreValue);
         Destroy(other.gameObject);
         Destroy(gameObject);
         //not about below section
         if (other.tag != "Player")
         {
             gameController.AddScore(scoreValue);
         }
     }
 }

Script being referenced:

using UnityEngine; using System.Collections;

public class SpaceShooter_GameController : MonoBehaviour { public GameObject hazard; public Vector3 spawnValues; public int hazardCount; public float spawnWait; public float startWait; public float waveWait;

 public GUIText scoreText;
 public int score;

 void Start ()
 {
     score = 0;
     UpdateScore ();
     StartCoroutine (SpawnWaves ());
 }
 
 IEnumerator SpawnWaves ()
 {
     yield return new WaitForSeconds (startWait);
     while (true) 
     {
         for (int i = 0; i < hazardCount; i++) {
             Vector3 spawnPosition = new Vector3 (Random.Range (-spawnValues.x, spawnValues.x), spawnValues.y, spawnValues.z);
             Quaternion spawnRotation = Quaternion.identity;
             Instantiate (hazard, spawnPosition, spawnRotation);
             yield return new WaitForSeconds (spawnWait);
         }
         yield return new WaitForSeconds (waveWait);
     }
 }

 public void AddScore (int newScoreValue)
 {
     score += newScoreValue;
     UpdateScore ();
 }

 void UpdateScore ()
 {
     scoreText.text = "Score:" + score;
 }

}

Thanks for your help in advance. Cheers

Sincerely Sanguine

K