I am getting this error when I tried to build for production. **ng build --prod --aot** ``` "angularfire2": "^5.0.0-rc.6", "@angular/compiler-cli": "^5.2.0", "@angular/cli": "~1.7.0", ``` ``` WARNING in ./src/app/app.module.ngfactory.js 110:18734-18740 "export 'ɵa' (imported as 'i47') was not found in 'angularfire2/firestore' ``` Works well with development **ng serve**.