fix(core,ui): address code review feedback

- Add null guard to BootstrapText.SafeFormat for null templates
- Make JTabView._maxTabsPerRow readonly
- Use evt.currentTarget instead of evt.target in JTabView handlers
- Add SafeFormat null template test

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: JasonXuDeveloper - 傑 <jason@xgamedev.net>

Author: JasonXuDeveloper

UnityProject/Packages/com.jasonxudeveloper.jengine.core/Runtime/BootstrapText.cs

@@ -151,10 +151,15 @@ public struct BootstrapText
 
         /// <summary>
         /// Safe wrapper around <see cref="string.Format(string, object[])"/> that falls back
-        /// to the raw template if the user-edited format string is malformed.
+        /// to a safe value if the user-edited format string is malformed or null.
         /// </summary>
         public static string SafeFormat(string template, params object[] args)
         {
+            if (string.IsNullOrEmpty(template))
+            {
+                return string.Empty;
+            }
+
             try
             {
                 return string.Format(template, args);

UnityProject/Packages/com.jasonxudeveloper.jengine.ui/Editor/Components/Navigation/JTabView.cs

@@ -41,7 +41,7 @@ public class JTabView : VisualElement
         private readonly List<Label> _tabButtons = new();
         private readonly List<VisualElement> _contentPanels = new();
         private int _selectedIndex = -1;
-        private int _maxTabsPerRow;
+        private readonly int _maxTabsPerRow;
 
         /// <summary>
         /// Creates a new tab view with a tab bar and content area.
@@ -202,7 +202,7 @@ private static void ApplyInactiveStyle(Label tab)
 
         private static void OnTabClicked(MouseDownEvent evt)
         {
-            if (evt.target is Label tab && tab.userData is int index)
+            if (evt.currentTarget is Label tab && tab.userData is int index)
             {
                 // Walk up to find the JTabView parent
                 var parent = tab.parent?.parent;
@@ -215,15 +215,15 @@ private static void OnTabClicked(MouseDownEvent evt)
 
         private void OnTabMouseEnter(MouseEnterEvent evt)
         {
-            if (evt.target is Label tab && tab.userData is int index && index != _selectedIndex)
+            if (evt.currentTarget is Label tab && tab.userData is int index && index != _selectedIndex)
             {
                 tab.style.backgroundColor = Tokens.Colors.BgHover;
             }
         }
 
         private void OnTabMouseLeave(MouseLeaveEvent evt)
         {
-            if (evt.target is Label tab && tab.userData is int index && index != _selectedIndex)
+            if (evt.currentTarget is Label tab && tab.userData is int index && index != _selectedIndex)
             {
                 tab.style.backgroundColor = StyleKeyword.None;
             }

UnityProject/Packages/com.jasonxudeveloper.jengine.ui/Tests/Editor/Components/Navigation/JTabViewTests.cs

@@ -570,7 +570,7 @@ public void OnTabClicked_SelectsCorrectTab()
             Assert.IsNotNull(method, "OnTabClicked method should exist");
 
             var evt = (MouseDownEvent)Activator.CreateInstance(typeof(MouseDownEvent), true);
-            evt.target = secondTab;
+            evt.currentTarget = secondTab;
             method.Invoke(null, new object[] { evt });
 
             Assert.AreEqual(1, _tabView.SelectedIndex);
@@ -585,7 +585,7 @@ public void OnTabClicked_WithNonLabelTarget_DoesNothing()
                 BindingFlags.NonPublic | BindingFlags.Static);
 
             var evt = (MouseDownEvent)Activator.CreateInstance(typeof(MouseDownEvent), true);
-            evt.target = new VisualElement();
+            evt.currentTarget = new VisualElement();
             method.Invoke(null, new object[] { evt });
 
             Assert.AreEqual(0, _tabView.SelectedIndex);
@@ -605,7 +605,7 @@ public void OnTabMouseEnter_InactiveTab_SetsHoverBackground()
             Assert.IsNotNull(method, "OnTabMouseEnter method should exist");
 
             var evt = (MouseEnterEvent)Activator.CreateInstance(typeof(MouseEnterEvent), true);
-            evt.target = inactiveTab;
+            evt.currentTarget = inactiveTab;
             method.Invoke(_tabView, new object[] { evt });
 
             Assert.AreEqual(Tokens.Colors.BgHover, inactiveTab.style.backgroundColor.value);
@@ -624,7 +624,7 @@ public void OnTabMouseEnter_ActiveTab_DoesNotChangeBackground()
             var method = typeof(JTabView).GetMethod("OnTabMouseEnter",
                 BindingFlags.NonPublic | BindingFlags.Instance);
             var evt = (MouseEnterEvent)Activator.CreateInstance(typeof(MouseEnterEvent), true);
-            evt.target = activeTab;
+            evt.currentTarget = activeTab;
             method.Invoke(_tabView, new object[] { evt });
 
             Assert.AreEqual(expectedBg, activeTab.style.backgroundColor.value);

UnityProject/Packages/com.jasonxudeveloper.jengine.ui/Tests/Editor/Internal/BootstrapEditorUITests.cs

@@ -677,6 +677,13 @@ public void SafeFormat_EmptyTemplate_ReturnsEmpty()
             Assert.AreEqual("", result);
         }
 
+        [Test]
+        public void SafeFormat_NullTemplate_ReturnsEmpty()
+        {
+            var result = BootstrapText.SafeFormat(null, "arg");
+            Assert.AreEqual(string.Empty, result);
+        }
+
         #endregion
 
         #region BootstrapText Default Tests