Traceback (most recent call last):
  File "/usr/lib/tinyerp-client/modules/gui/main.py", line 690, in _sig_child_call
    res = wid.handlers[button_name][1]()
  File "/usr/lib/tinyerp-client/modules/gui/window/form.py", line 309, in sig_action
    res = obj.exec_keyword(keyword, {'model':self.screen.resource, 'id': id or False, 'ids':ids, 'report_type': report_type}, adds=adds)
  File "/usr/lib/tinyerp-client/modules/action/main.py", line 136, in exec_keyword
    self._exec_action(action, data)
  File "/usr/lib/tinyerp-client/modules/action/main.py", line 109, in _exec_action
    wizard.execute(action['wiz_name'], datas)
  File "/usr/lib/tinyerp-client/modules/action/wizard.py", line 104, in execute
    if 'datas' in res:
TypeError: argument of type 'NoneType' is not iterable