Can't set localeDetection in the next-i18next.config

I hope everything is alright since this is my very first report. I just tried to upgrade my nextjs application. Which worked fine so far. But when I try to build the application I get an error:

🐛 Bug Report

Type error: Argument of type '{ i18n: { locales: string[]; defaultLocale: string; localeDetection: boolean; }; debug: boolean; nonExplicitSupportedLngs: boolean; reloadOnPrerender: boolean; trailingSlash: boolean; }' is not assignable to parameter of type 'UserConfig'.
  Types of property 'i18n' are incompatible.
    Type '{ locales: string[]; defaultLocale: string; localeDetection: boolean; }' is not assignable to type 'NextJsI18NConfig'.
      Object literal may only specify known properties, and 'localeDetection' does not exist in type 'NextJsI18NConfig'.

To Reproduce

the next-i18next.config.js looks like this:

module.exports = {
  i18n: {
    locales: ['default', 'de', 'en'],
    defaultLocale: 'en',
    localeDetection: false,
  },
  debug: process.env.NODE_ENV === 'development',
  nonExplicitSupportedLngs: true,
  reloadOnPrerender: process.env.NODE_ENV === 'development',
  trailingSlash: true,
};

our _app.page.tsx looks like this:

import { appWithTranslation } from 'next-i18next';
import nextI18NextConfig from '../../next-i18next.config.js';
...

export default appWithTranslation(MyApp, nextI18NextConfig);

Expected behaviour

I would expect that the method appWithTranslation/UserConfig accepts the property localeDetection. Since nextjs would accept it by default. I used this approach to always have the language in the URL https://nextjs.org/docs/advanced-features/i18n-routing

Our Environment

node v16.14.0 “next”: “13.0.6”, “next-i18next”: “^13.0.0”, “i18next”: “^22.0.8”, “react-i18next”: “^12.0.0”,

[adrai]

changing that to boolean would not solve it… The problem is next.js itself is defining it as false here and here … and on the installed next.js version it is included in node_modules/next/dist/next-config-validate.js as boolean… This means the Vercel team (@Timer) needs to adapt their types first to be boolean instead of false everywhere.

[belgattitude]

Thx for mention, I’m still off a couple of days but I’ll read properly soon and see what we can do.