Invalid libraries override specification exception in Drupal 8

So i was trying to override all the JavaScript a parent theme was adding by doing this in my subtheme:

libraries-override:
  bulma/global:
    js: false

That gave a big old fatal error when trying to load a page after a cache reload:

Drupal\Core\Asset\Exception\Invalid Libraries Override SpecificationException: Library asset bulma/global/js is not correctly specified. It should be in the form “extension/library_name/sub_key/path/to/asset.js”. in Drupal\Core\Asset\LibraryDiscoveryParser->applyLibrariesOverride() (line 407 of /var/www/drupal/web/core/lib/Drupal/Core/Asset/LibraryDiscoveryParser.php).