Not existing context not detected as type error if covered by string union

[stefan-schweiger]

🐛 Bug Report

When you use a string union as the context parameter it's possible to supply values for which a context does not exist and it does not result in an error. If you just use the plain string value or a const it works.

To Reproduce

A minimal reproducible example.

{
  "translation": {
    "testContext1_Test1": "EN: Context1 Test1",
    "testContext1_Test2": "EN: Context1 Test2",
  },
}

const App = () => {
  const { t } = useTranslation('translation');

  return (
    <div>
      <p>
        {t('testContext1', { context: 'Test1' as 'Test1' | 'Test2' | 'Test3' })}
      </p>
      <p>{t('testContext1', { context: 'Test2' })}</p>
      <p>{t('testContext1', { context: 'Test2' as const })}</p>
      <p>
        {t('testContext1', { context: 'Test3' as 'Test1' | 'Test2' | 'Test3' })}
      </p>
      {/* Error: Type '{ context: "Test3"; }' is not assignable to type 'string' */}
      <p>{t('testContext1', { context: 'Test3' })}</p>
      {/* Error: Type '{ context: "Test3"; }' is not assignable to type 'string' */}
      <p>{t('testContext1', { context: 'Test3' as const })}</p>
    </div>
  );
};

Expected behavior

String unions should be correctly detected as errors if they have cases which are not covered by the context.

Your Environment

• runtime version: i.e. node v14, deno, browser xy
• i18next version: i.e. 19.5.3
• os: Mac, Windows, Linux
• any other relevant information

[marcalexiei]

This issue is an upstream issue, so it should be handled in i18next not react-i18next.
@adrai can the issue be moved there or it needs to be closed and reopened there?

[stefan-schweiger]

Thanks, I have reopened the issue in i18next.