Allow styles to be saved as empty so that other contrib modules can provide styles

Interesting question! 😊

The module that alters in those styles is the one that is responsible for ensuring things are correct, because it means parts of the editor.editor.*.yml config no longer live in that config, but in that module's hook_editor_js_settings_alter().

Therefore I think you'd want something like:

/**
 * Implements hook_config_schema_info_alter().
 */
function MYMODULE_config_schema_info_alter(&$definitions) {
  // This module alters in the styles for the `ckeditor5_style` plugin, so adjust the config schema's validation constraints.
  unset($definitions['ckeditor5.plugin.ckeditor5_style']['mapping']['styles']['constraints']['NotBlank']);
}

That single line would allow you to do what you want in your custom module on that particular project, but allow Drupal core to ensure a reliable, consistent UX when using CKEditor 5.

Curious about your thoughts! 😊

Automatically closed - issue fixed for 2 weeks with no activity.