Created attachment 478586 [details] error I'm modifying the reddit-panel example so that it quits when finished (for bug 594076), but doing so results in the attached error. The destructor assumes that this._frame has been initialized, but that's not the case if the module is unloaded before _initFrame has been called. The reddit-panel example uses a contentURL, not a frame, so "frame" is not in the options object passed to the constructor, which means that _initFrame is called when the hidden frame is ready, which does not occur before the module is unloaded and the destructor is called.
Created attachment 478587 [details] [diff] [review] patch This just sticks the destructor in an `if (this._frame)` conditional.
Comment on attachment 478587 [details] [diff] [review] patch Looks great! I had the same fix in my patch for bug 596018, which I've just checked in, however, so this is now resolved.
The Add-on SDK is no longer a Mozilla Labs experiment and has become a big enough project to warrant its own Bugzilla product, so the "Add-on SDK" product has been created for it, and I am moving its bugs to that product. To filter bugmail related to this change, filter on the word "looptid".