call close on the barcode scanning client

@@ -472,4 +472,11 @@ class MobileScanner(
         camera?.cameraControl?.setZoomRatio(1f)
     }
 
+    /**
+     * Dispose of this scanner instance.
+     */
+    fun dispose() {
+        scanner?.close()
+        scanner = null
+    }
 }

@@ -92,6 +92,7 @@ class MobileScannerHandler(
     fun dispose(activityPluginBinding: ActivityPluginBinding) {
         methodChannel?.setMethodCallHandler(null)
         methodChannel = null
+        mobileScanner?.dispose()
         mobileScanner = null
 
         val listener: RequestPermissionsResultListener? = permissions.getPermissionListener()