update web error code handling to handle unsupported better

@@ -17,6 +17,9 @@ class ScannerErrorWidget extends StatelessWidget {
       case MobileScannerErrorCode.permissionDenied:
         errorMessage = 'Permission denied';
         break;
+      case MobileScannerErrorCode.unsupported:
+        errorMessage = 'Scanning is unsupported on this device';
+        break;
       default:
         errorMessage = 'Generic Error';
         break;

@@ -11,4 +11,7 @@ enum MobileScannerErrorCode {
 
   /// The permission to use the camera was denied.
   permissionDenied,
+
+  /// Scanning is unsupported on the current device.
+  unsupported,
 }

@@ -207,9 +207,21 @@ class MobileScannerController {
     } on PlatformException catch (error) {
       MobileScannerErrorCode errorCode = MobileScannerErrorCode.genericError;
 
-      if (error.code == "MobileScannerWeb") {
+      final String? errorMessage = error.message;
+
+      if (kIsWeb) {
+        if (errorMessage == null) {
+          errorCode = MobileScannerErrorCode.genericError;
+        } else if (errorMessage.contains('NotFoundError') ||
+            errorMessage.contains('NotSupportedError')) {
+          errorCode = MobileScannerErrorCode.unsupported;
+        } else if (errorMessage.contains('NotAllowedError')) {
           errorCode = MobileScannerErrorCode.permissionDenied;
+        } else {
+          errorCode = MobileScannerErrorCode.genericError;
         }
+      }
+
       isStarting = false;
 
       throw MobileScannerException(