macos: change to NSMenu extension

macos/Sources/Features/Terminal/Window Styles/TerminalWindow.swift

@@ -299,23 +299,8 @@ class TerminalWindow: NSWindow {
         item.identifier = Self.closeTabsOnRightMenuItemIdentifier
         item.target = nil
         item.isEnabled = true
-        
-        // Remove any previously configured items, because the menu is
-        // cached across different tab targets.
-        if let existing = menu.items.first(where: { $0.identifier == item.identifier }) {
-            menu.removeItem(existing)
-        }
-
-        // Insert it wherever we can
-        if let idx = menu.items.firstIndex(where: {
-            $0.action == NSSelectorFromString("performCloseOtherTabs:")
-        }) {
-            menu.insertItem(item, at: idx + 1)
-        } else if let idx = menu.items.firstIndex(where: {
-            $0.action == NSSelectorFromString("performClose:")
-        }) {
-            menu.insertItem(item, at: idx + 1)
-        } else {
+        if !menu.insertItem(item, after: NSSelectorFromString("performCloseOtherTabs:")) &&
+           !menu.insertItem(item, after: NSSelectorFromString("performClose:")) {
             menu.addItem(item)
         }
     }

macos/Sources/Helpers/Extensions/NSMenu+Extension.swift

@@ -0,0 +1,29 @@
+import AppKit
+
+extension NSMenu {
+    /// Inserts a menu item after an existing item with the specified action selector.
+    ///
+    /// If an item with the same identifier already exists, it is removed first to avoid duplicates.
+    /// This is useful when menus are cached and reused across different targets.
+    ///
+    /// - Parameters:
+    ///   - item: The menu item to insert.
+    ///   - action: The action selector to search for. The new item will be inserted after the first
+    ///             item with this action.
+    /// - Returns: `true` if the item was inserted after the specified action, `false` if the action
+    ///            was not found and the item was not inserted.
+    @discardableResult
+    func insertItem(_ item: NSMenuItem, after action: Selector) -> Bool {
+        if let identifier = item.identifier,
+           let existing = items.first(where: { $0.identifier == identifier }) {
+            removeItem(existing)
+        }
+
+        guard let idx = items.firstIndex(where: { $0.action == action }) else {
+            return false
+        }
+
+        insertItem(item, at: idx + 1)
+        return true
+    }
+}