add rejection to UF search promises when an empty list is returned

Prevents responses from providers that respond first, but with empty results, from being considered as the final result
fix BrasilAPI#600

pages/api/ibge/municipios/v1/[uf].js

@@ -9,13 +9,14 @@ import InternalError from '@/errors/InternalError';
 import BaseError from '@/errors/BaseError';
 
 import { getCities } from '@/services/dados-abertos-br/cities';
+import { rejectWhenEmptyArray } from '@/services/util/rejectWhenEmptyArray';
 
 const getData = async (uf, providers = null) => {
   const promises = [];
   if (!providers) {
-    promises.push(getContiesByUf(uf));
-    promises.push(getCities(uf));
-    promises.push(getStateCities(uf));
+    promises.push(rejectWhenEmptyArray(getContiesByUf(uf)));
+    promises.push(rejectWhenEmptyArray(getCities(uf)));
+    promises.push(rejectWhenEmptyArray(getStateCities(uf)));
   } else {
     if (providers.includes('wikipedia')) {
       promises.push(getStateCities(uf));

services/util/rejectWhenEmptyArray.js

@@ -0,0 +1,13 @@
+/**
+ * Rejects the promise if the data is an empty array.
+ *
+ * @param {Promise} promise
+ * @returns {Promise}
+ */
+export async function rejectWhenEmptyArray(promise) {
+  const data = await promise;
+  if (!data || data.length === 0) {
+    throw new Error('Empty data');
+  }
+  return data;
+}