Previewing comment widget on staging/preview page

Hello! I'm testing out Comentario on Publii. Publii generates local previews, and opens files like the following in the browser:

file:///C:/Users/user/Documents/Publii/sites/my-site/preview/preview.html

I've been able to test comment widgets in the past from this local preview, but I run into the following error with Comentario:

Error: body.host in body is required.

{
  "status": 422,
  "message": "",
  "response": "{\"code\":602,\"message\":\"body.host in body is required\"}"
}

I understand that it checks for the registered domain, but I'm trying to test to see whether my installation works, and what styling I'll need to do, without publishing to the live site.