How to resolve : error : failed to process add chd-cannot read property last child ?

Hi ,

I am getting below error when i login into cockpit and try searching for products. error :failed to process add chd-cannot read property last child of null while after adding product to cnd clicking on checkout

I have attached screen shot as well. Please let me know what does this error mean and how it can be resolved.

[1]: /storage/temp/6489-cockpit-zk-issue.png