Error when creating module field group

[esedic]

I tried to create a new module field group. When I click "Add group" button I get javascript error in console:

Uncaught TypeError: Cannot read property 'innerHTML' of null

This is the source of error:

(function() {with (this[2]) {with (this[1]) {with (this[0]) {return function(event){addGroup($('addGroupName').value);
};}}}})

I'm testing on localhost on latest Joomla 3.4.1