You have to uninstall it first, then goto node_modules folder then @ionic-native folder then delete the barcode scanner folder. Then go back to your terminal then run npm i @ionic-native/plugin-name@4 --save
You have to uninstall it first, then goto node_modules folder then @ionic-native folder then delete the barcode scanner folder. Then go back to your terminal then run npm i @ionic-native/plugin-name@4 --save