This is a bit of an edge case, but if an accordion component is added which does not contain any _items, the setUpItems function here (https://github.com/adaptlearning/adapt_framework/blob/master/src/core/js/models/itemsComponentModel.js#L24) fails and never runs for any subsequent components. As such the toJSON() call in the same code fails because _children is null and prevents the course from rendering.
This is a bit of an edge case, but if an accordion component is added which does not contain any _items, the
setUpItemsfunction here (https://github.com/adaptlearning/adapt_framework/blob/master/src/core/js/models/itemsComponentModel.js#L24) fails and never runs for any subsequent components. As such thetoJSON()call in the same code fails because_childrenis null and prevents the course from rendering.