Debugging Ember JS -- Identifying line in code that causes an error

So I'm getting the following error:

Uncaught Error: Assertion Failed: The key provided to get must be a string, you passed undefined

Should be easy enough to fix, if there was any indication of the line in my code that causes that error.

Using the chrome console, I click on ember.debug.js:6254 next to the error, which just shows me the ember code that throws the error. I can expand the error, but I just get a bunch of functions that can't be clicked on and no indication where they come from.

Can someone please help me figure out how to identify the line in my Ember code that is causing the error.