2019-09-15 17:42:43 ERROR (MainThread) [homeassistant.core] Error executing service <ServiceCall google.scan_for_calendars (xxxxxxxxxxxxxxxxxxxxxxxxxxxxx)>
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/core.py", line 1243, in _safe_execute
    await self._execute_service(handler, service_call)
  File "/usr/src/homeassistant/homeassistant/core.py", line 1262, in _execute_service
    await self._hass.async_add_executor_job(handler.func, service_call)
  File "/usr/local/lib/python3.7/concurrent/futures/thread.py", line 57, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/usr/src/homeassistant/homeassistant/components/google/__init__.py", line 255, in _scan_for_calendars
    service = calendar_service.get()
  File "/usr/src/homeassistant/homeassistant/components/google/__init__.py", line 349, in get
    http = credentials.authorize(httplib2.Http())
AttributeError: 'NoneType' object has no attribute 'authorize'