@dobbel Yes, I even added it to the window scope.
Problem more likely the priority of loading the plugin.
When the quasar start, it tend to loaded the vuex store before cordova plugin did, hence it will get undefined in state.js .
So in the end I solved it with the phonegap-plugin-barcodescanner, which is very similar to the cordova-plugin-barcodescanner, but you can configure it, so it feels more like a QR scanner.
Be aware that it the two above internally (in cordova) register/use the same name, so before changing from the cordova plugin to the phonegap one, remove it with the command below before adding the another one, so the build process won’t break.
$ cordova plugin rm cordova-plugin-barcodescanner