MANDATORY_SETTER_FUNCTION assertion causes errors on Component teardown with HTMLBars

[benlesh]

I'm currently consistantly running into an issue where Ember setting view.element = null; apparently on this line in HTMLBars

Causes an assertion error that is unhandled and breaking our app. Here's a screenshot:

[benlesh]

This is specifically happening somewhere within the ember-nf-graph nf-graph-content component

... and it only started after I upgraded to Ember 1.11.1.

[rwjblue]

element is not an observable property, observing it would cause this error

[rwjblue]

I did a quick scan through the repo, and do not see an instance of you observing element. It could either be in a consuming application, or something like the inspector (having the inspector open can cause all properties on the object that is selected to be observed).

[benlesh]

The only thing I can think of is that I'm accessing that DOM element via something like D3 in another component.

FWIW: I looked through version history and found that it used to use set in that area: 6af9b03#diff-d8303a7a1692ae012d56a3c6dad4ed2dL139

[benlesh]

... but access it via D3 wouldn't cause that right?

It seems like something set up the element property on that component to have this default getter that does the assertion. I'm not sure where that is set up or why.

[rwjblue]

if you use another views element in a template somewhere else (I don't even know if that would work), the template usage would setup an observer on element and cause this error.

[rwjblue]

So, I suppose it depends how you use the element...

[benlesh]

That's probably what's happening. nf-graph get's the nf-graph-content's element and sets up some events on it I think.

[benlesh]

Bingo

That's the culprit, I'd wager. Thanks @rwjblue

[benlesh]

FWIW: Because Ember is so consistent, this seems like a "wat" in Ember. Everything else in Ember is delightfully uniform or at least gives you clean errors/assertions if you abuse a thing. As an author, I just assumed that Ember, being Ember, would allow me to observe, depend on, or get damn near anything