Failed to perform the action evri.track_a_parcel. Unknown error / TypeError: 'NoneType' object is not subscriptable

[ethzero]

Hi,
When using the Developer Tools > Actions > evri.track_a_parcel method I'm getting error returned the following when attempting to the Perform the action:
"Failed to perform the action evri.track_a_parcel. Unknown error"

action: evri.track_a_parcel
data:
  tracking_number: H06R4A005[REDACTED]

There appears to be a corresponding error in the Home Assistant Core log of the following; I believe the significant line is:

TypeError: 'NoneType' object is not subscriptable

Full entry:

Logger: homeassistant.helpers.script.websocket_api_script
Source: helpers/script.py:524
First occurred: 13:10:11 (5 occurrences)
Last logged: 13:23:54

websocket_api script: Error executing script. Unexpected error for call_service at pos 1: 'NoneType' object is not subscriptable
Traceback (most recent call last):
  File "/usr/src/homeassistant/homeassistant/helpers/script.py", line 524, in _async_step
    await getattr(self, handler)()
  File "/usr/src/homeassistant/homeassistant/helpers/script.py", line 1009, in _async_step_call_service
    response_data = await self._async_run_long_action(
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    ...<9 lines>...
    )
    ^
  File "/usr/src/homeassistant/homeassistant/helpers/script.py", line 624, in _async_run_long_action
    return await long_task
           ^^^^^^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/core.py", line 2835, in async_call
    response_data = await coro
                    ^^^^^^^^^^
  File "/usr/src/homeassistant/homeassistant/core.py", line 2878, in _execute_service
    return await target(service_call)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/config/custom_components/evri/services.py", line 75, in track_a_parcel
    most_recent_tracking_event = coordinator.data.get(CONF_RESULTS)[0][
                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^
TypeError: 'NoneType' object is not subscriptable

[ethzero]

Digging a little deeper I think the URL/apikey is faulting as the following PowerShell of....

 $headers = @{
  "apiKey"        = "RGVplG9He66OnnAjnGKz7Ovol9dKbSAr"
}
Invoke-RestMethod `
 -Uri "https://api.hermesworld.co.uk/enterprise-tracking-api/v1/parcels/search/[REDACTED]" `
 -Headers $headers `
 -Method Get

.. returns:

Invoke-RestMethod:
{
  "error": "Forbidden"
}