Error in Apple's TVML documentation? pushPage function doesn't work - tvos

Question

UPDATED 6/1/17 with the correct code pasted at the bottom.
I'm working through Apple's TVML guide, section 2: Navigating Between Pages. (https://developer.apple.com/library/content/documentation/TVMLKitJS/Conceptual/TVMLProgrammingGuide/NavigatingBetweenPages.html#//apple_ref/doc/uid/TP40016718-CH9-SW1)
Everything is fine until the last bit (Listing 4-4), which allow you to use the menu button on the remote to return to the previous page. Whenever I try it, my sample app simply won't load:
var baseURL;
function loadingTemplate() {
var template = '<document><loadingTemplate><activityIndicator><text>Loading</text></activityIndicator></loadingTemplate></document>';
var templateParser = new DOMParser();
var parsedTemplate = templateParser.parseFromString(template, "application/xml");
return parsedTemplate;
}
function getDocument(extension) {
var templateXHR = new XMLHttpRequest();
var url = baseURL + extension;
var loadingScreen = loadingTemplate();
templateXHR.responseType = "document";
templateXHR.addEventListener("load", function() {pushPage(templateXHR.responseXML, loadingScreen);}, false);
templateXHR.open("GET", url, true);
templateXHR.send();
}
function pushPage(page, loading) {
var currentDoc = getActiveDocument();
navigationDocument.replaceDocument(page, loading);
}
App.onLaunch = function(options) {
baseURL = options.BASEURL;
var extension = "templates/InitialPage.xml";
getDocument(extension);
}
What am I missing?
This works:
var baseURL;
function loadingTemplate() {
var template = '<document><loadingTemplate><activityIndicator><text>Loading</text></activityIndicator></loadingTemplate></document>';
var templateParser = new DOMParser();
var parsedTemplate = templateParser.parseFromString(template, "application/xml");
navigationDocument.pushDocument(parsedTemplate);
return parsedTemplate;
}
function getDocument(extension) {
var templateXHR = new XMLHttpRequest();
var url = baseURL + extension;
var loadingScreen = loadingTemplate();
templateXHR.responseType = "document";
templateXHR.addEventListener("load", function() {pushPage(templateXHR.responseXML, loadingScreen);}, false);
templateXHR.open("GET", url, true);
templateXHR.send();
}
function pushPage(page, loading) {
navigationDocument.replaceDocument(page, loading);
}
App.onLaunch = function(options) {
baseURL = options.BASEURL;
var extension = "templates/InitialPage.xml";
getDocument(extension);
}

Answer 1

Yes, I believe there is a mistake. They should have kept the line
navigationDocument.pushDocument(parsedTemplate);
at the end of the loadingTemplate method.
The idea is to push the loading page, then replace it with the new page.
On a side note, the line
var currentDoc = getActiveDocument();
has no business here. This code was obviously not tested or reviewed.