Cannot read property 'Keyboard' of undefined

Hello,

Suddenly (without changing anything I can think of) I get an error in my console "Cannot read property ‘Keyboard’ of undefined"
I tried executing cordova plugin add com.ionic.keyboard but it gives me another error "Registry returned 404 for GET on https://registry.npmjs.org/com.ionic.keyboard"
My IDE (webstorm) does recognize the “keyboard” in my app.js after executing cordova plugin add ionic-plugin-keyboard, but I still get the error in my console.

How can I solve this?