Broken with 404 on main.css/main.js

Problem/Motivation

* Installed the module and its deps on current D8.8
* The explorer page itself on jsonapi-explorer/app?location=... has the correct 200 response and correct content
* The assets jsonapi-explorer/main.js(&.css) return a 404
* Debugging shows that the method \Drupal\jsonapi_explorer\Controller\AppProxyController::proxy is never reached in latter case

Setting critical as this makes the module unusable.

Proposed resolution

???