fix(api): map CHECK-constraint violation (empty key) to 422

crates/api/tests/admin_fields.rs

@@ -284,3 +284,24 @@ async fn create_authority_field(pool: PgPool) {
 
     assert_eq!(resp.status(), StatusCode::CREATED);
 }
+
+#[sqlx::test(migrations = "../db/migrations")]
+async fn empty_key_is_422(pool: PgPool) {
+    migrate_sessions(&db::Db::from_pool(pool.clone()))
+        .await
+        .unwrap();
+
+    seed_user(&pool, "ed@example.com", "pw-editor-123", Role::Editor).await;
+
+    let app = build_app(state(pool));
+    let cookie = login(&app, "ed@example.com", "pw-editor-123").await;
+
+    let resp = post_field(
+        &app,
+        &cookie,
+        r#"{"key":"","data_type":"text","required":false,"labels":[{"lang":"en","label":"X"}]}"#,
+    )
+    .await;
+
+    assert_eq!(resp.status(), StatusCode::UNPROCESSABLE_ENTITY);
+}