[unity] Handle BoneFollowerGraphic error on editor instantiate.

spine-unity/Assets/spine-unity/Modules/SkeletonGraphic/BoneFollowerGraphic.cs

@@ -66,8 +66,9 @@ namespace Spine.Unity {
 				bone = skeletonGraphic.Skeleton.FindBone(boneName);
 
 			#if UNITY_EDITOR
-			if (Application.isEditor)
+			if (Application.isEditor) {
 				LateUpdate();
+			}
 			#endif
 		}
 
@@ -91,7 +92,9 @@ namespace Spine.Unity {
 			var thisTransform = this.transform as RectTransform;
 			if (thisTransform == null) return;
 
-			float scale = skeletonGraphic.canvas.referencePixelsPerUnit;
+			var canvas = skeletonGraphic.canvas;
+			if (canvas == null) canvas = skeletonGraphic.GetComponentInParent<Canvas>();
+			float scale = canvas.referencePixelsPerUnit;
 
 			if (skeletonTransformIsParent) {
 				// Recommended setup: Use local transform properties if Spine GameObject is the immediate parent