firebase node bug

gistfile1.js

/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:95
is.o===m)&&nd(a)}};function Ed(a,b,c,d,e){for(var g=a.get(b),h=o,i=g.ma.length
                                                                    ^
TypeError: Cannot read property 'ma' of undefined
    at Ed (/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:95:211)
    at Fd (/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:96:88)
    at Bd.hc (/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:95:458)
    at Ld.r.hc (/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:108:258)
    at G.Ub (/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:13:136)
    at /Users/pwmckenna/git/todium-stats/lib/todium-tracker.js:12:31
    at id (/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:81:441)
    at md (/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:82:382)
    at jd.dc (/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:81:904)
    at Bd.dc (/Users/pwmckenna/git/todium-stats/node_modules/firebase/lib/firebase-node.js:97:472)

//WAS RUNNING THIS CODE

var Firebase = require('firebase');
var firebase = new Firebase('https://todium.firebaseio.com/');
var selector = firebase.child('trackers').child('bc7e7c9658546aaba6e43a3700141f7a89546db4').child('stats').child('started');

selector.startAt().limit(1).on('child_added', function () {
    console.log('start off');
    selector.startAt().limit(1).off('child_added');
});

selector.endAt().limit(100).on('child_added', function () {
    console.log('end off');
    selector.endAt().limit(1).off('child_added');
});