[unity] Fixed error message on entering Play mode when AnimationReferenceAsset selected. Closes #1892. Fixed NullReferenceException from SkeletonDataPreview timeline bar on entering Play mode. Closes #1893.

spine-unity/Assets/Spine/Editor/spine-unity/Editor/Asset Types/AnimationReferenceAssetEditor.cs

@@ -33,6 +33,7 @@ using UnityEngine;
 using UnityEditor;
 
 using System.Reflection;
+using System;
 
 namespace Spine.Unity.Editor {
 	using Editor = UnityEditor.Editor;
@@ -58,7 +59,11 @@ namespace Spine.Unity.Editor {
 		SkeletonData lastSkeletonData;
 
 		void OnEnable () { HandleOnEnablePreview(); }
-		void OnDestroy () { HandleOnDestroyPreview(); }
+		void OnDestroy () {
+			HandleOnDestroyPreview();
+			AppDomain.CurrentDomain.DomainUnload -= OnDomainUnload;
+			EditorApplication.update -= preview.HandleEditorUpdate;
+		}
 
 		public override void OnInspectorGUI () {
 			animationNameProperty = animationNameProperty ?? serializedObject.FindProperty("animationName");
@@ -133,6 +138,11 @@ namespace Spine.Unity.Editor {
 		void HandleOnEnablePreview () {
 			if (ThisSkeletonDataAsset != null && ThisSkeletonDataAsset.skeletonJSON == null)
 				return;
+			SpineEditorUtilities.ConfirmInitialization();
+
+			// This handles the case where the managed editor assembly is unloaded before recompilation when code changes.
+			AppDomain.CurrentDomain.DomainUnload -= OnDomainUnload;
+			AppDomain.CurrentDomain.DomainUnload += OnDomainUnload;
 
 			preview.Initialize(this.Repaint, ThisSkeletonDataAsset, LastSkinName);
 			preview.PlayPauseAnimation(ThisAnimationName, true);
@@ -142,6 +152,10 @@ namespace Spine.Unity.Editor {
 			EditorApplication.update += preview.HandleEditorUpdate;
 		}
 
+		private void OnDomainUnload (object sender, EventArgs e) {
+			OnDestroy();
+		}
+
 		private void HandleOnSkinChanged (string skinName) {
 			EditorPrefs.SetString(LastSkinKey, skinName);
 			preview.PlayPauseAnimation(ThisAnimationName, true);

spine-unity/Assets/Spine/Editor/spine-unity/Editor/Asset Types/SkeletonDataAssetInspector.cs

@@ -1158,7 +1158,7 @@ namespace Spine.Unity.Editor {
 			float lineRectWidth = lineRect.width;
 			TrackEntry t = skeletonAnimation.AnimationState.GetCurrent(0);
 
-			if (t != null) {
+			if (t != null && Icons.userEvent != null) { // when changing to play mode, Icons.userEvent  will not be reset
 				int loopCount = (int)(t.TrackTime / t.TrackEnd);
 				float currentTime = t.TrackTime - (t.TrackEnd * loopCount);
 				float normalizedTime = currentTime / t.Animation.Duration;
@@ -1176,14 +1176,15 @@ namespace Spine.Unity.Editor {
 				for (int i = 0; i < currentAnimationEvents.Count; i++) {
 					float eventTime = currentAnimationEventTimes[i];
 					var userEventIcon = Icons.userEvent;
+					float iconX = Mathf.Max(((eventTime / t.Animation.Duration) * lineRectWidth) - (userEventIcon.width / 2), barRect.x);
+					float iconY = barRect.y + userEventIcon.height;
 					var evRect = new Rect(barRect) {
-						x = Mathf.Max(((eventTime / t.Animation.Duration) * lineRectWidth) - (userEventIcon.width / 2), barRect.x),
-						y = barRect.y + userEventIcon.height,
+						x = iconX,
+						y = iconY,
 						width = userEventIcon.width,
 						height = userEventIcon.height
 					};
 					GUI.DrawTexture(evRect, userEventIcon);
-
 					Event ev = Event.current;
 					if (ev.type == EventType.Repaint) {
 						if (evRect.Contains(ev.mousePosition)) {