FIREBASE WARNING: set at /contacts/-MSXfNR-YOwHn0ve5V7D failed: permission_denied code example

Example: Uncaught (in promise) Error: PERMISSION_DENIED: Permission denied at Repo.ts:632

firebase.auth().signInAnonymously().catch(function(error) {
  // Handle Errors here.
  var errorCode = error.code;
  var errorMessage = error.message;
  // ...
});