Scanning failed: Class not found

[Umar]

Did any one use Phonegap-plugin-barcodescanner,when i want read QR code i have problem “scanning failed:class not found”.
There is my code

<template>
      <q-btn color="primary" label="Scan QR code"
             @click="scan()"></q-btn>
</template>

<script>
export default {
  name: 'Index',
  methods: {
    scan () {
      cordova.plugins.barcodeScanner.scan(
      
              function (result) {
      
                alert('We got a barcode\n' +
      
                  'Result: ' + result.text + '\n' +
      
                  'Format: ' + result.format + '\n' +
      
                  'Cancelled: ' + result.cancelled)
      
              },
      
              function (error) {
      
                alert('Scanning failed: ' + error)
      
              }
      
            )
}
</script>