Exception for offline systems

[pbaylas]

I'm getting a lot of this exception (about 90 per hour with 5 systems connected to Beszel):

 AttributeError:'NoneType' object has no attribute 'items'
File "homeassistant/helpers/update_coordinator.py" , line 203 , in async_update_listeners
     update_callback()
File "homeassistant/helpers/update_coordinator.py" , line 662 , in _handle_coordinator_update
     self.async_write_ha_state()
File "homeassistant/helpers/entity.py" , line 1054 , in async_write_ha_state
     self._async_write_ha_state()
File "homeassistant/helpers/entity.py" , line 1203 , in _async_write_ha_state
     ) = self.__async_calculate_state()
File "homeassistant/helpers/entity.py" , line 1114 , in __async_calculate_state
     if extra_state_attributes := self.extra_state_attributes:
File "/config/custom_components/beszel_api/sensor.py" , line 448 , in extra_state_attributes
     for key, value in temperatures.items(): 

Looking at the data collected by sentry for these errors, it seems that it's only happening for servers that are offline. I have a few laptops connected to my bezel server, so there is pretty much always at least one or two offline.

This is with version 1.0.1 of the home assistant integration connected to version 0.18.7 of Beszel server.