The issue is that sometimes records[i] is outside of the bounds of the collection.
Not entirely sure why, or what this method is meant to be doing, but it could probably be a bit more defensive I think.
I'm generally seeing it on the last child node... have kind of worked around it for now, but it's leaves the UI in a mess.
Basically overridden my tree view's updateIndexes, and put a try..catch around callParent; meaning I get nodes staying in the tree, but at least I can keep testing, which is sufficient for my current focus.
I am still getting this error in 4.0.2. Your fix seems to work great (as I am no longer getting errors in my console window). Are the Sencha team aware of this?
That's a good question. I've been assured that this is the correct forum for bug reports, and that Sencha WILL get to all of them, despite the current backlog. I take them at their word. It's a big backlog, though!
Well, I did post this what seems like ages ago now!
I've started posting a few issues in the premium forums since stands a better chance of getting spotted. Shame really, since the bugs and help forums used to see a lot more activity from the devs, especially during the developer previews.
I get the impression Ext 4 is 'done' now though, so would stick with overriding things yourself if I were you