How to suppres inexistence of attribute

Configuration
1

Hello
I have specific sensor which collects a lot of data in its attributes which are json objects

sensor.doorwindow_counter.attributes.counter.obj1.json_data
sensor.doorwindow_counter.attributes.counter.obj2.json_data 
etc

where json_data is for example

{
    "count" : 0,
    "time_reset": ...,
    "time_last": ....
}

the point is, that objX may not exist at time of filling another template which references those data. See count attribute in template below

  - platform: template
    sensors:
      child_room_window:
        friendly_name: "Child Room Window"
        device_class: "window"
        attribute_templates:
          battery: >-
            {{ state_attr('binary_sensor.child_room_window_battery','battery') }}
          tilt: >-
            {{ state_attr('binary_sensor.child_room_window_tilt','tilt') }}
          count: >-
            {{ state_attr('sensor.doorwindow_counter','counters')['child_room_window_state']['count'] }}

It will fail if sensor.doorwindow_counter.attributes.counters.child_room_window_state doesn’t exist.
Inexistence of count attribut is not critical, it can be suppresed by default(0).

But how can I suppress inexistence of the the first level key in counters object?
probably I could check existence first, then decide if go deeper or not. But in case of yet deeper structure it would have code havoc. Is there a nice way how to cope whith such situation?

2

I think that’s what you will have to do. Perhaps something like this:

          count: >-
            {% set c = state_attr('sensor.doorwindow_counter','counters') %}
            {{ c.child_room_window_state.count | default(0) if c.child_room_window_state else 'unknown' }}