Gojs internal error : Cannot read property 'Yc' of null

Hello, walter.

I’ve got this message while moving a node right after that I changed the node type.
Would you please check what is the reason for this?

I’m sorry, but I cannot tell from those error messages.

Please see this video.

I’ve implemented type change with fast-key ‘t’ like below.

function onKeyDown() {
    if (kptn == '   T') {
        var sel = _d.selection;
        if (sel.count == 0) return;


        var it = sel.iterator;
        while(it.next()) {
            var cat = it.value.part.category;
            if (cat == 'RefNode') {
                _d.model.setDataProperty(it.value.part.data, 'category', 'GoToNode');
            else if (cat == 'GoToNode') {
                _d.model.setDataProperty(it.value.part.data, 'category', 'RefNode');
            else {
                warning(`cannot change type for '${cat}'`, "Type Change");


Thank you!

That code to change the category of some selected Parts looks fine. The problem is either in how those templates are defined or in some tool customization that you have.