chore: Fix video stories

lib/pages/story/story_page.dart

@@ -196,16 +196,18 @@ class StoryPageController extends State<StoryPage> {
 
   String get roomId => VRouter.of(context).pathParameters['roomid'] ?? '';
 
-  Future<VideoPlayerController>? loadVideoControllerFuture;
+  Future<VideoPlayerController?>? loadVideoControllerFuture;
 
-  Future<VideoPlayerController> loadVideoController(Event event) async {
+  Future<VideoPlayerController?> loadVideoController(Event event) async {
     try {
       final matrixFile = await event.downloadAndDecryptAttachment();
+      if (!mounted) return null;
       final tmpDirectory = await getTemporaryDirectory();
       final fileName =
           event.content.tryGet<String>('filename') ?? 'unknown_story_video.mp4';
       final file = File(tmpDirectory.path + '/' + fileName);
       await file.writeAsBytes(matrixFile.bytes);
+      if (!mounted) return null;
       final videoPlayerController =
           _videoPlayerController = VideoPlayerController.file(file);
       await videoPlayerController.initialize();

lib/pages/story/story_view.dart

@@ -72,7 +72,7 @@ class StoryView extends StatelessWidget {
           ),
         ),
         actions: [
-          if (!controller.isOwnStory)
+          if (!controller.isOwnStory && currentEvent != null)
             AnimatedOpacity(
               duration: const Duration(seconds: 1),
               opacity: controller.isHold ? 0 : 1,
@@ -159,7 +159,7 @@ class StoryView extends StatelessWidget {
               children: [
                 if (event.messageType == MessageTypes.Video &&
                     PlatformInfos.isMobile)
-                  FutureBuilder<VideoPlayerController>(
+                  FutureBuilder<VideoPlayerController?>(
                     future: controller.loadVideoControllerFuture ??=
                         controller.loadVideoController(event),
                     builder: (context, snapshot) {