fix: def programming on canvas hide

Author: jcs090218

Assets/JCSUnity/Scripts/UI/JCS_Canvas.cs

@@ -374,6 +374,9 @@ public void Hide(bool mute = false)
 
         private void HideEnable()
         {
+            if (mCanvas == null)
+                return;
+
             mCanvas.enabled = false;
 
             if (mCanvasGroup != null)
@@ -382,6 +385,9 @@ private void HideEnable()
 
         private void HideFade()
         {
+            if (mCanvas == null)
+                return;
+
             // Remains enabled since we're going to do fading.
             mCanvas.enabled = true;