fix: bounds-safe action bar focus node access

lib/focus/focusable_action_bar.dart

@@ -88,8 +88,12 @@ class FocusableActionBarState extends State<FocusableActionBar> {
   late List<FocusNode> _focusNodes;
   late List<bool> _focusStates;
 
-  /// Access a focus node by index (e.g. for external `requestFocus()` calls).
-  FocusNode getFocusNode(int index) => _focusNodes[index];
+  FocusNode? getFocusNode(int index) =>
+      index >= 0 && index < _focusNodes.length ? _focusNodes[index] : null;
+
+  void requestFocusOnFirst() {
+    if (_focusNodes.isNotEmpty) _focusNodes.first.requestFocus();
+  }
 
   @override
   void initState() {

lib/screens/discover_screen.dart

@@ -188,7 +188,7 @@ class _DiscoverScreenState extends State<DiscoverScreen>
     if (_isHeroSectionVisible) {
       _heroFocusNode.requestFocus();
     } else {
-      _actionBarKey.currentState?.getFocusNode(0).requestFocus();
+      _actionBarKey.currentState?.requestFocusOnFirst();
     }
     _scrollToTop();
   }
@@ -275,7 +275,7 @@ class _DiscoverScreenState extends State<DiscoverScreen>
       final keys = _allHubKeys;
       if (keys.isNotEmpty) keys.first.currentState?.requestFocusFromMemory();
     },
-    onUp: () => _actionBarKey.currentState?.getFocusNode(0).requestFocus(),
+    onUp: () => _actionBarKey.currentState?.requestFocusOnFirst(),
     onLeft: () {
       if (_currentHeroIndex > 0) {
         _heroController.previousPage(duration: tokens(context).slow, curve: Curves.easeInOut);
@@ -824,7 +824,7 @@ class _DiscoverScreenState extends State<DiscoverScreen>
     final actionBar = _actionBarKey.currentState;
     if (actionBar == null) return;
     final lastNode = actionBar.getFocusNode(actionBar.widget.actions.length - 1);
-    final RenderBox? button = lastNode.context?.findRenderObject() as RenderBox?;
+    final RenderBox? button = lastNode?.context?.findRenderObject() as RenderBox?;
     if (button == null) return;
 
     final RenderBox overlay = Navigator.of(context).overlay!.context.findRenderObject() as RenderBox;

lib/screens/focusable_detail_screen_mixin.dart

@@ -47,10 +47,7 @@ mixin FocusableDetailScreenMixin<T extends StatefulWidget> on State<T>, GridFocu
     setState(() {
       isAppBarFocused = true;
     });
-    final state = actionBarKey.currentState;
-    if (state != null && getAppBarActions().isNotEmpty) {
-      state.getFocusNode(0).requestFocus();
-    }
+    actionBarKey.currentState?.requestFocusOnFirst();
     // Scroll to top to show the app bar
     scrollController.animateTo(0, duration: const Duration(milliseconds: 200), curve: Curves.easeOut);
   }

lib/screens/libraries/libraries_screen.dart

@@ -821,7 +821,7 @@ class _LibrariesScreenState extends State<LibrariesScreen>
               i,
               onSelectWhenActive: _focusCurrentTab,
               onNavigateDown: _focusCurrentTabFromTabBar,
-              onNavigateRightFromLast: () => _actionBarKey.currentState?.getFocusNode(0).requestFocus(),
+              onNavigateRightFromLast: () => _actionBarKey.currentState?.requestFocusOnFirst(),
             ),
           ],
         ],
@@ -965,7 +965,7 @@ class _LibrariesScreenState extends State<LibrariesScreen>
               i,
               onSelectWhenActive: _focusCurrentTab,
               onNavigateDown: _focusCurrentTabFromTabBar,
-              onNavigateRightFromLast: () => _actionBarKey.currentState?.getFocusNode(0).requestFocus(),
+              onNavigateRightFromLast: () => _actionBarKey.currentState?.requestFocusOnFirst(),
             ),
                             ],
                           ],

lib/screens/livetv/live_tv_screen.dart

@@ -339,7 +339,7 @@ class _LiveTvScreenState extends State<LiveTvScreen>
                       i,
                       onSelectWhenActive: _focusCurrentTab,
                       onNavigateDown: _focusCurrentTab,
-                      onNavigateRightFromLast: () => _actionBarKey.currentState?.getFocusNode(0).requestFocus(),
+                      onNavigateRightFromLast: () => _actionBarKey.currentState?.requestFocusOnFirst(),
                     ),
                   ],
                 ],
@@ -421,7 +421,7 @@ class _LiveTvScreenState extends State<LiveTvScreen>
                       i,
                       onSelectWhenActive: _focusCurrentTab,
                       onNavigateDown: _focusCurrentTab,
-                      onNavigateRightFromLast: () => _actionBarKey.currentState?.getFocusNode(0).requestFocus(),
+                      onNavigateRightFromLast: () => _actionBarKey.currentState?.requestFocusOnFirst(),
                     ),
                   ],
                 ],