HighlightJS not working with block call

I'm trying to get Highlight.JS working and am running into the following error when I call the hljs.highlightBlock() call:

TypeError: Cannot read property 'replace' of undefined

This error comes from the highlight.pack.js file and because its minimized it was hard to tell where exactly but I beautified it and it the error seems to be coming from this line (line 7 in the beautified script):

function n(e) {
    return e.replace(/&/gm, "&amp;").replace(/</gm, "&lt;").replace(/>/gm, "&gt;")
}

Here's a little more context showing my current DOM environment. First off you can see that I have identified a code block in the DOM (myDom) and also that the hljs object is available:

But then, just to demonstrate from the browser's CLI it failing:

I'm including the Ember community in this too just in case it has something to do with the recent "ember-disable-prototype-extensions" module now being included in addons for Ember-CLI.