Refactor code structure for improved readability and maintainability

test/limits.test.js

@@ -14,7 +14,7 @@ test("Импорт: не больше двух разборов сразу, ли
       active--;
     });
   const running = [task(), task(), task()];
-  await assert.rejects(task(), (e) => e.status === 429 && e.message === "Занято");
+  await assert.rejects(task(), (e) => e.status === 429 && e.code === "busy" && e.message === "Занято");
   // Each finished task hands its slot to the one waiting.
   while (release.length) {
     release.shift()();
@@ -47,6 +47,10 @@ test("Импорт: лимит запросов считается по адре
   };
   assert.ok(call("10.0.0.1").passed);
   assert.ok(call("10.0.0.1").passed);
-  assert.deepEqual(call("10.0.0.1"), { status: 429, body: { error: "Подождите" }, passed: false });
+  assert.deepEqual(call("10.0.0.1"), {
+    status: 429,
+    body: { error: "Подождите", code: "too_many_requests" },
+    passed: false,
+  });
   assert.ok(call("10.0.0.2").passed);
 });