Traceback (most recent call last):
  File "/usr/lib/ubiquity/plugins/ubi-usersetup.py", line 371, in info_loop
    self.hostname_error(make_error_string(self.controller, errors))
  File "/usr/lib/ubiquity/plugins/ubi-usersetup.py", line 73, in make_error_string
    return "\n".join([controller.get_string(error) for error in errors])
TypeError: sequence item 0: expected str instance, NoneType found