Property 'firebase' does not exist on type { production: boolean; }

Question

So I was trying to build and deploy my Angular 4 app for production on both Firebase and Heroku, but I have come across the error as follows:

ERROR in /U

Answer 1

I hate duplicates in code
so let's create a separate file named environments/firebase.ts with content

export const firebase = {
    //...
};

the usage

import {firebase} from '../environments/firebase';
//...
AngularFireModule.initializeApp(firebase)

all is clear as for me