Pathologic was missing because of a .git folder inside.

[yaffs-website] / web / modules / contrib / advagg / advagg_mod / advagg_mod.routing.yml

advagg_mod.settings:
  path: '/admin/config/development/performance/advagg/mod'
  defaults:
    _form: 'Drupal\advagg_mod\Form\SettingsForm'
    _title: 'AdvAgg: Modifications'
  requirements:
    _permission: 'administer site configuration'