trackLocation = ({ onSuccess, onError = () => { } }) => {
    if ('geolocation' in navigator === false) {
        return onError(new Error('Geolocation is not supported by your browser.'));
    }

    return navigator.geolocation.watchPosition(onSuccess, onError, {
        enableHighAccuracy: true,
        timeout: 5000,
        maximumAge: 0
    });
}
Track the user location.
@param {Object} onSuccess
@param {Object} [onError]
@return {number}