Create a trigger based on resource person type

Hi,

We need to create a trigger based on the PersonType attribute of the Resource object. The logic should be as follows:

if(PersonType='EMP'){
  setAttribute(newField_c,'Internal')}
else return null

Our goal is to ensure that when a Resource is created, if the PersonType is EMP, a custom field is populated with a specific value.

However, when we try to compose this trigger in App Composer (on the Resource object), we encounter the following error:

Error(1,4) : Unknown attribute name: PersonType for type: Resource

Is there a way to achieve this requirement? How can we access the PersonType attribute correctly?