修复Chart在运行时被删除时会异常报错的问题 (#269)

Runtime/Internal/Object/ChartLabel.cs

@@ -55,10 +55,17 @@ namespace XCharts.Runtime
 
         protected override void Awake()
         {
+            base.Awake();
             raycastTarget = false;
             SetActive(true);
         }
 
+        protected override void OnDestroy()
+        {
+            base.OnDestroy();
+            GraphicRegistry.UnregisterGraphicForCanvas(canvas, this);
+        }
+
         public void SetTextPadding(TextPadding padding)
         {
             m_PaddingLeft = padding.left;