With a barebone ezpublish.yml:

siteaccess:
list:

• site_user
• site_admin
  groups:
  admin_group: [site_admin, site_user]
  frontend_group: [site_user]
  default_siteaccess: site_user
  match:
  Map\URI:
  site_user: site_user
  site_admin: site_admin
  Map\Host:
  publish.dev: site_user
  admin.publish.dev: site_admin

system:
site_user:
user:
layout: AcmeCoreBundle::pagelayout.html.twig
location_view:
full:
frontpage:
template: "AcmeCoreBundle::landingpage.html.twig"
match:
Identifier\ContentType: "landing_page"

An exception is thrown while rendering the page.