问Geolocation.currentLocation()不工作，使用meteor(1.5.1) & mdg:geolocation(1.3.0)给出空值

EN

// Continous geolocation with mdg:geolocation
// This code will run every time user location changes.

Tracker.autorun(() => {
  const position = Geolocation.currentLocation();

  Tracker.nonreactive(() => {
    if (position) {
      Meteor.call('user.update.position', position);
    }
  });
});

// Navigation geolocation to get geolocation only once
let errorCallback;
let successCallback;

successCallback = position => Meteor.call('user.update.position', position);
errorCallback = err => console.log(err);

navigator.geolocation.getCurrentPosition(successCallback, errorCallback, {
  maximumAge: 60000,
  timeout: 20000
});