Private Term Autocomplete widget

The image upload ajax is broken with the Private Term Field with Autocomplete field display.

Error Code

Uncaught AjaxError:
An AJAX HTTP error occurred.
HTTP Result Code: 200
Debugging information follows.
Path: /node/add/blog?element_parents=field_cover/widget/0&ajax_form=1
StatusText: OK
ResponseText:

And the site went white screen upon saving without image upload with following warning.

The website encountered an unexpected error. Please try again later.

No problem with select list, but this is not user friendly.
Please look into this ASAP.

Drupal 8.0.2
Private Taxonomy 8.x-1.0-alpha1