Calling render() on PanelManager breaks style manager

In lieu of #540, I'm trying to manually remove a button from the options panel, with this:

let pnm = editor.Panels;
pnm.getPanel('options').get('buttons').remove(pnm.getButton('options', 'gjs-open-import-template'));
pnm.render()

This works ok, the button goes away, but the pnm.render() seems to break the style manager, in that it becomes unresponsive. Non of the other stuff seems to break, just the styling. Is this a problem I'm introducing or a bug?

Thanks!