Go to the create new event dialog
Click on edit language (example)
Decide you do not want to set a language
Try to get rid of the language field
The list of values passed to the selection doesn't have a empty value (because "" can't be a key), however the default value is set to "". When angularJS sees a value that is not in the list it creates the empty option as it doesn't want to select one for you. Once you've selected a value the empty option is removed.
So we need to add a valid blank option, either by putting it in the html or adding it to the array of values (again hard as this appears to be key: value map)