How to get if all all objects are destroyed to start another wave

I am making a simple shooter. I want the following: to keep track of current enemies. if there are no enemies I want to start the new wave. My game controller code currently looks like this: using System.Collections; using System.Collections.Generic; using UnityEngine;

 public class GameController : MonoBehaviour {
 
     public GameObject[] Bosses;
 
     public GameObject[] Enemies;
 
     public int EnemyCount = 3;
 
     public float SpawnWait = 0.1f;
 
     public float StartWait = 1f;
 
     public float WaveWait = 1f;
 
     private float waveNumber = 1;
 
     void Start () {
         StartCoroutine(SpawnWaves());
     }
 
     private IEnumerator SpawnWaves()
     {
         yield return new WaitForSeconds(StartWait);
 
         while (true)
         {
 
             Debug.Log("Starting Wave");
             if (GameObject.FindGameObjectWithTag("Enemy") != null)
                 continue;
 
             if (waveNumber % 3 == 1 && waveNumber > 1)
             {
                 Debug.Log("Sending New Enemy");
                 float spawnCoordY = Random.Range(-4, 4);
                 Vector2 spawnPosition = new Vector2(5, spawnCoordY);
 
                 System.Random random = new System.Random();
                 int enemyToSpawnIndex = random.Next(0, Bosses.Length);
 
                 GameObject currentEnemy = Instantiate(Bosses[enemyToSpawnIndex], spawnPosition,
                     Quaternion.identity);
             }
             else
             {
 
                 for (int i = 0; i < EnemyCount; i++)
                 {
                     float spawnCoordY = Random.Range(-4, 4);
                     Vector2 spawnPosition = new Vector2(5, spawnCoordY);
                     System.Random random = new System.Random();
                     int enemyToSpawnIndex = random.Next(0, Enemies.Length);
 
                     GameObject currentEnemy = Instantiate(Enemies[enemyToSpawnIndex], spawnPosition,
                         Quaternion.identity);
 
                     yield return new WaitForSeconds(SpawnWait);
                 }
 
                 EnemyCount += 2;
             }
 
             waveNumber++;
             yield return new WaitForSeconds(WaveWait);
 
         }
     }
 }

As you can see, I check if all enemies have been destroyed by seeking for enemy with tag and if no enemy is found I start next wave. For unspecified reason it has some problems. Sometimes it freezes the game (and the editor itself). I know the problem is there because when I comment out that line it works well. Please tell me what is the main problem of it ? and also if there is a better practice of doing what I want do not hesitate to also tell it to me.