Log and provide a UnityEvent for when `Rigidbody.IsSleeping` changes.

SleepHelper.cs

#if UNITY_EDITOR
using UnityEditor;
#endif

using System;
using UnityEngine;
using UnityEngine.Assertions;
using UnityEngine.Events;

namespace UGS.unityutils {
	/// <summary>
	/// Log and provide a UnityEvent for when `Rigidbody.IsSleeping` changes.
	/// </summary>
	public sealed class SleepHelper : MonoBehaviour {
#if UNITY_EDITOR

		[SerializeField]
		private Rigidbody rb = null;

		public void OnValidate() {
			if (null == rb) {
				Undo.RecordObject(this, "Set RB");
				rb = GetComponent<Rigidbody>();
			}
			Assert.IsNotNull(rb, $"{name} has no rb");
		}

		public void OnEnable() {
			lastSleeping = rb.IsSleeping();
		}

		public void FixedUpdate() {
			var newSleeping = rb.IsSleeping();
			if (newSleeping != lastSleeping) {
				Debug.Log($"{Time.frameCount}: {name}.sleeping:{lastSleeping}->{newSleeping}", this);
				lastSleeping = newSleeping;
				SleepingChanged.Invoke(newSleeping);
			}
		}

		[Tooltip("Invoked with the new status")]
		public UnityBoolEvent SleepingChanged;

		[Serializable]
		public sealed class UnityBoolEvent : UnityEvent<bool> {}

		private bool lastSleeping;

#endif // UNITY_EDITOR
	}
}