Error while trying to edit nested component via SmartEdit

Hi there, The problem is that I get an error in the browser console, while trying to open nested component:

"TypeError: Cannot read property 'toLowerCase' of undefined"

It happens because in function editComponent (which is in cmsItemDropdown.js) itemToEdit.typeCode is undefiened. But why and when it should be set up I can't figure out. If anybody have faced with such problem and could help - I'd really appreciate your help! Thanks in advance!