Using includes with jsreport not working

[masull]

We get the following when including a pug template in jsreport studio.
Error while executing templating engine. the "filename" option is required to use includes and extends with "relative" paths

doctype html
html(lang='en')
head
title Pug
body
h1 Pug Examples
div.container
p Cool Pug example!
each row in cxEmployees
each value, field in row
!= t1(field)
include includes/test4.pug