Translations not applied to captcha plugin errors

[samerset-rmn]

Description

Hi, thanks for the great library! I think I’ve found a bug – translations are not applied to errors from the captcha plugin.

I’m using a custom getLocale function, but it doesn’t seem to be called when captcha errors occur. With standard better-auth errors, everything works as expected: getLocale is called and returns the correct locale and the plugin applies the translation to the error.

Expected behavior

When the captcha plugin throws an error (VERIFICATION_FAILED, MISSING_RESPONSE or UNKNOWN_ERROR), it should be returned in the detected language.

Actual behavior

VERIFICATION_FAILED, MISSING_RESPONSE and UNKNOWN_ERROR are always returned in English.

Versions

better-auth: 1.5.6
better-auth-localization: 3.0.0

Localization setup

Better-auth plugins are configured as follows:

plugins: [
  customSession(), 
  captchaPlugin({
    provider: 'cloudflare-turnstile',
    secretKey: process.env.TURNSTILE_SECRET_KEY!
  }),
  username(), 
  localizationPlugin({
    defaultLocale: 'default',
    fallbackLocale: 'default',
    getLocale: getLocale
  })
]

Steps to reproduce

Minimal example:

// Backend
export const auth = betterAuth({
  database: drizzleAdapter(db, { provider: 'mysql', schema: authSchema }),
  plugins: [
    captcha({ 
      provider: 'cloudflare-turnstile', 
      secretKey: '1x0000000000000000000000000000000AA' // Test key
    }),
    localization({
      defaultLocale: 'default',
      fallbackLocale: 'default',
      getLocale: () => {
        console.log('getLocale is called');
        return 'ru-RU';
      }
    })
  ]
});

// Frontend (locale 'ru-RU' is sent with headers)
const response = await authClient.signUp.email({
  email: 'test@test.com',
  password: 'qwerty123'
});

console.log(response);
// {
//     "data": null,
//     "error": {
//         "message": "Missing CAPTCHA response", // Not "Ответ CAPTCHA отсутствует"
//         "code": "MISSING_RESPONSE",
//         "status": 400,
//         "statusText": "Bad Request"
//     }
// }