Config doesn't load if keys aren't strings

[dmyates]

This doesn't load:

{
  apiKey: "API_KEY",
  authDomain: "PROJECT_ID.firebaseapp.com",
  databaseURL: "https://PROJECT_ID.firebaseio.com",
  projectId: "PROJECT_ID",
  storageBucket: "PROJECT_ID.appspot.com",
  messagingSenderId: "SENDER_ID",
  appId: "APP_ID",
  measurementId: "G-MEASUREMENT_ID",
}

This works fine:

{
  "apiKey": "API_KEY",
  "authDomain": "PROJECT_ID.firebaseapp.com",
  "databaseURL": "https://PROJECT_ID.firebaseio.com",
  "projectId": "PROJECT_ID",
  "storageBucket": "PROJECT_ID.appspot.com",
  "messagingSenderId": "SENDER_ID",
  "appId": "APP_ID",
  "measurementId": "G-MEASUREMENT_ID",
}