fix bug in app lifecycle guidance

@@ -7,6 +7,9 @@ Improvements:
 * [web] Added the size information to barcode results.
 * Added support for barcode formats to image analysis.
 * Updated the scanner to report any scanning errors that were encountered during processing.
+* Introduced a new getter `hasCameraPermission` for the `MobileScannerState`.
+* Fixed a bug in the lifecycle handling sample. Now instead of checking `isInitialized`,
+the sample recommends using `hasCameraPermission`, which also guards against camera permission errors.
 
 Bugs fixed:
 * Fixed a bug that would cause the scanner to emit an error when it was already started. Now it ignores any calls to start while it is starting.

@@ -127,7 +127,7 @@ class MyState extends State<MyStatefulWidget> with WidgetsBindingObserver {
   void didChangeAppLifecycleState(AppLifecycleState state) {
     // If the controller is not ready, do not try to start or stop it.
     // Permission dialogs can trigger lifecycle changes before the controller is ready.
-    if (!controller.value.isInitialized) {
+    if (!controller.value.hasCameraPermission) {
       return;
     }
 
@@ -192,4 +192,4 @@ Future<void> dispose() async {
 To display the camera preview, pass the controller to a `MobileScanner` widget.
 
 See the [examples](example/README.md) for runnable examples of various usages,
-such as the basic usage, applying a scan window, or retrieving images from the barcodes.
+such as the basic usage, applying a scan window, or retrieving images from the barcodes.
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