fix: dispose of media controller

lib/ui/add_page/widgets/add_page.dart

@@ -23,13 +23,19 @@ class AddPage extends StatefulWidget {
 
 class _AddPageState extends State<AddPage> {
   num? price;
+  final MobileScannerController controller = MobileScannerController(
+    formats: [BarcodeFormat.ean13],
+    detectionTimeoutMs: 1000,
+  );
+
+  @override
+  void dispose() {
+    controller.dispose();
+    super.dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
-    final MobileScannerController controller = MobileScannerController(
-      formats: [BarcodeFormat.ean13],
-      detectionTimeoutMs: 1000,
-    );
-
     final theme = Theme.of(context);
     // return Consumer<TabScreen>(
     // builder: (context, screen, child) {

lib/ui/sell_page/widgets/scan_screen.dart

@@ -18,6 +18,13 @@ class _ScanScreenState extends State<ScanScreen> {
     formats: [BarcodeFormat.ean13],
     detectionTimeoutMs: 1000,
   );
+
+  @override
+  void dispose() {
+    controller.dispose();
+    super.dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);