fix: 🐛 use flattened attrs to capture oidc field errors

addons/api/addon/adapters/application.js

@@ -248,7 +248,11 @@ export default class ApplicationAdapter extends RESTAdapter.extend(
     // Normalize field-specific errors, if any.
     const errors = fieldErrors.map((error) => ({
       detail: error.description,
-      source: { pointer: `/data/attributes/${error.name}` },
+      // Ember Data cannot handle errors on nested attributes, so these are
+      // flattened (e.g. `attributes.foobar` becomes `attributes_foobar`).
+      // To capture these errors, add read-only fields on the model
+      // corresponding to the underscored field name.
+      source: { pointer: `/data/attributes/${error.name.replace('.', '_')}` },
     }));
     // Return a list of JSON API errors rooted under the `errors` key.
     return {

addons/api/addon/models/auth-method.js

@@ -1,4 +1,5 @@
 import GeneratedAuthMethodModel from '../generated/models/auth-method';
+import { attr } from '@ember-data/model';
 import { fragment } from 'ember-data-model-fragments/attributes';
 import { equal } from '@ember/object/computed';
 
@@ -27,6 +28,26 @@ export const options = {
 };
 
 export default class AuthMethodModel extends GeneratedAuthMethodModel {
+  // =error attributes
+  // These attributes exist solely to capture errors on nested fields.
+  // See the application adapter's error normalization method for
+  // more information.
+
+  @attr('string', { readOnly: true }) attributes_state;
+  @attr('string', { readOnly: true }) attributes_issuer;
+  @attr('string', { readOnly: true }) attributes_client_id;
+  @attr('string', { readOnly: true }) attributes_client_secret;
+  @attr('string', { readOnly: true }) attributes_max_age;
+  @attr('string', { readOnly: true }) attributes_api_url_prefix;
+  @attr('string', { readOnly: true })
+  attributes_disable_discovered_config_validation;
+  @attr('string', { readOnly: true }) attributes_dry_run;
+  @attr('string', { readOnly: true }) attributes_account_claim_maps;
+  @attr('string', { readOnly: true }) attributes_claims_scopes;
+  @attr('string', { readOnly: true }) attributes_signing_algorithms;
+  @attr('string', { readOnly: true }) attributes_allowed_audiences;
+  @attr('string', { readOnly: true }) attributes_idp_ca_certs;
+
   // =attributes
 
   /**