HotReload.cs

using System.Collections.Generic;
using System.Linq;
using UnityEngine;
using UnityEngine.SceneManagement;
#if UNITY_EDITOR
using UnityEditor;
#endif

public class HotReload : MonoBehaviour
{
#if UNITY_EDITOR
	[HideInInspector] [SerializeField] private bool isCompiling;
	[HideInInspector] [SerializeField] private List<string> currentScenes;

	private static bool instanced;

	public void OnEnable()
	{
		if (instanced)
		{
			Destroy(gameObject);
			return;
		}

		DontDestroyOnLoad(gameObject);
		instanced = true;
	}

	public void Update()
	{
		if (isCompiling == false && EditorApplication.isCompiling)
		{
			Debug.Log($"{EditorApplication.timeSinceStartup:0.00} compile start");
			isCompiling = true;

			currentScenes = new List<string>();
			for (var x = 0; x < SceneManager.sceneCount; x++)
			{
				currentScenes.Add(SceneManager.GetSceneAt(x).name);
			}
		}

		if (isCompiling && !EditorApplication.isCompiling)
		{
			SceneManager.LoadScene(currentScenes[0]);
			foreach (var scene in currentScenes.Skip(1))
			{
				SceneManager.LoadScene(scene, LoadSceneMode.Additive);
			}
			Debug.Log($"{EditorApplication.timeSinceStartup:0.00} compile finish");
			isCompiling = false;
		}
	}
#endif
}