fix: Add workaround for OpenTelemetry/Zone.js

packages/next-intl/.size-limit.ts

@@ -9,7 +9,7 @@ const config: SizeLimitConfig = [
   {
     name: "import * from 'next-intl' (react-server)",
     path: 'dist/production/index.react-server.js',
-    limit: '14.735 KB'
+    limit: '15.355 KB'
   },
   {
     name: "import {createSharedPathnamesNavigation} from 'next-intl/navigation' (react-client)",
@@ -21,13 +21,13 @@ const config: SizeLimitConfig = [
     name: "import {createLocalizedPathnamesNavigation} from 'next-intl/navigation' (react-client)",
     path: 'dist/production/navigation.react-client.js',
     import: '{createLocalizedPathnamesNavigation}',
-    limit: '4.115 KB'
+    limit: '4.125 KB'
   },
   {
     name: "import {createNavigation} from 'next-intl/navigation' (react-client)",
     path: 'dist/production/navigation.react-client.js',
     import: '{createNavigation}',
-    limit: '4.115 KB'
+    limit: '4.125 KB'
   },
   {
     name: "import {createSharedPathnamesNavigation} from 'next-intl/navigation' (react-server)",
@@ -55,7 +55,7 @@ const config: SizeLimitConfig = [
   {
     name: "import * from 'next-intl/server' (react-server)",
     path: 'dist/production/server.react-server.js',
-    limit: '14.035 KB'
+    limit: '14.635 KB'
   },
   {
     name: "import createMiddleware from 'next-intl/middleware'",

packages/next-intl/__mocks__/react.tsx

@@ -1,10 +1,12 @@
+import {isPromise} from '../src/shared/utils';
+
 // @ts-expect-error -- React uses CJS
 export * from 'react';
 
 export {default} from 'react';
 
 export function use(promise: Promise<unknown> & {value?: unknown}) {
-  if (!(promise instanceof Promise)) {
+  if (!isPromise(promise)) {
     throw new Error('Expected a promise, got ' + typeof promise);
   }
 

packages/next-intl/src/navigation/shared/createSharedNavigationFns.tsx

@@ -16,7 +16,7 @@ import {
   Pathnames
 } from '../../routing/types';
 import {ParametersExceptFirst, Prettify} from '../../shared/types';
-import {isLocalizableHref} from '../../shared/utils';
+import {isLocalizableHref, isPromise} from '../../shared/utils';
 import BaseLink from './BaseLink';
 import {
   HrefOrHrefWithParams,
@@ -111,10 +111,9 @@ export default function createSharedNavigationFns<
     const isLocalizable = isLocalizableHref(href);
 
     const localePromiseOrValue = getLocale();
-    const curLocale =
-      localePromiseOrValue instanceof Promise
-        ? use(localePromiseOrValue)
-        : localePromiseOrValue;
+    const curLocale = isPromise(localePromiseOrValue)
+      ? use(localePromiseOrValue)
+      : localePromiseOrValue;
 
     const finalPathname = isLocalizable
       ? getPathname(

packages/next-intl/src/react-server/index.test.tsx

@@ -1,6 +1,7 @@
 import React from 'react';
 import {describe, expect, it, vi} from 'vitest';
 import {getTranslations} from '../server.react-server';
+import {isPromise} from '../shared/utils';
 import {renderToStream} from './testUtils';
 import {
   _createCache,
@@ -73,7 +74,7 @@ describe('performance', () => {
     try {
       useTranslations('Component');
     } catch (promiseOrError) {
-      if (promiseOrError instanceof Promise) {
+      if (isPromise(promiseOrError)) {
         await promiseOrError;
         useTranslations('Component');
       } else {

packages/next-intl/src/server/react-server/RequestLocale.tsx

@@ -1,15 +1,14 @@
 import {headers} from 'next/headers';
 import {cache} from 'react';
 import {HEADER_LOCALE_NAME} from '../../shared/constants';
+import {isPromise} from '../../shared/utils';
 import {getCachedRequestLocale} from './RequestLocaleCache';
 
 async function getHeadersImpl(): Promise<Headers> {
   const promiseOrValue = headers();
 
   // Compatibility with Next.js <15
-  return promiseOrValue instanceof Promise
-    ? await promiseOrValue
-    : promiseOrValue;
+  return isPromise(promiseOrValue) ? await promiseOrValue : promiseOrValue;
 }
 const getHeaders = cache(getHeadersImpl);
 

packages/next-intl/src/server/react-server/getConfig.tsx

@@ -6,6 +6,7 @@ import {
   _createIntlFormatters,
   initializeConfig
 } from 'use-intl/core';
+import {isPromise} from '../../shared/utils';
 import {getRequestLocale} from './RequestLocale';
 import {getRequestLocale as getRequestLocaleLegacy} from './RequestLocaleLegacy';
 import createRequestConfig from './createRequestConfig';
@@ -72,7 +73,7 @@ See also: https://next-intl.dev/docs/usage/configuration#i18n-request
   };
 
   let result = getConfig(params);
-  if (result instanceof Promise) {
+  if (isPromise(result)) {
     result = await result;
   }
 

packages/next-intl/src/shared/utils.tsx

@@ -233,3 +233,10 @@ function comparePathnamePairs(a: string, b: string): number {
 export function getSortedPathnames(pathnames: Array<string>) {
   return pathnames.sort(comparePathnamePairs);
 }
+
+export function isPromise<Value>(
+  value: Value | Promise<Value>
+): value is Promise<Value> {
+  // https://github.com/amannn/next-intl/issues/1711
+  return typeof (value as any).then === 'function';
+}