// When you run ng build --prod angular-cli will use the environment.prod.ts file
// and your environment.prod.ts files environment variable doesn't have the firebase
// field hence you are getting the exception.
export const environment = {
production: true,
firebase: {
apiKey: "...",
authDomain: "project.firebaseapp.com",
databaseURL: "https://project.firebaseio.com",
projectId: "project",
storageBucket: "project.appspot.com",
messagingSenderId: "..."
}
};