addChildren throws error when ext-grid is hidden

[yangjuncode]

the callstack is below:

jquery.fancytree.grid.js?8b9c:807 Uncaught (in promise) TypeError: Cannot set property 'ftnode' of undefined
at Fancytree.nodeRender (jquery.fancytree.grid.js?8b9c:807)
at Fancytree.eval [as nodeRender] (jquery.fancytree.js?f020:335)
at Fancytree._callHook (jquery.fancytree.js?f020:2785)
at FancytreeNode.render (jquery.fancytree.js?f020:1961)
at FancytreeNode.addChildren (jquery.fancytree.js?f020:667)
at VueComponent.asyncNodeSelectStatus (addressBook.vue?3315:284)

[mar10]

Thank you for contributing! 👍

It looks like you're using Vue.js? Does the problem occur without that framework as well?

In order to process your issue, we need some more information, explanation what already was tried and/or concrete data.

A debuggable example (jsFiddle, Plunkr, CodePen, ...) may be helpful.

Please read the Contribution Guidelines for some hints on how to submit helpful feature requests and bug reports.

[yangjuncode]

some info is missing, the tree is in a display none div.
the attach is my modified demo.
when tree init ok, click add children button will trigger the error.
sample-ext-grid.html.zip

[yangjuncode]

@mar10
thanks for fixing, but i have a small question about the code.
i have commented on commit 5d93514.

[mar10]

1/0 does evaluate to NaN, which is falsy, so this line

newCount = Math.floor(free / trHeight) || 0;

is a hack for

newCount = trHeight ? Math.floor(free / trHeight) : 0;

which would be more clear, I admit.

[yangjuncode]

the two version is not equal at least in firefox:

var free=10
undefined
var trHeight=0
undefined
Math.floor(free / trHeight) || 0
Infinity
trHeight ? Math.floor(free / trHeight) : 0;
0

thanks for the un-hack version anyway.