Fix some unhandled exceptions due to missing null checks

[OverloadUT]

Description:

Fixed a couple cases that would produce errors when the ISY node status was None or -inf.

Related issue (if applicable): fixes #9384

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

[dethpickle]

Thanks @OverloadUT. I can't honestly say when the fans portion went away, but under 0.78.3 its no longer there. There still is a different start up ISY thing which looks similar:

Error doing job: Task exception was never retrieved
Traceback (most recent call last):
  File "/usr/local/lib/python3.6/site-packages/homeassistant/helpers/entity_platform.py", line 344, in _async_add_entity
    await entity.async_update_ha_state()
  File "/usr/local/lib/python3.6/site-packages/homeassistant/helpers/entity.py", line 235, in async_update_ha_state
    state = self.state
  File "/usr/local/lib/python3.6/site-packages/homeassistant/components/isy994.py", line 475, in state
    return super().state
  File "/usr/local/lib/python3.6/site-packages/homeassistant/helpers/entity.py", line 425, in state
    return STATE_ON if self.is_on else STATE_OFF
  File "/usr/local/lib/python3.6/site-packages/homeassistant/components/light/isy994.py", line 34, in is_on
    return self.value > 0
TypeError: '>' not supported between instances of 'NoneType' and 'int'

But, I cannot say where the fans ended and this one started. I can't even say that the above isn't my problem... other than, like the fans, everything seems to be working - just getting a couple of these on startup. So yes and yes to your questions over in #9384.

Thanks!

[OverloadUT]

@dethpickle The fan issue went away with my big refactor to the isy994 component many months ago.

This PR fixes both the cover and light errors :)

[dethpickle]

Fabulous. I appreciate the attention and look forward to the next release!