Preventing languages from getting out of sync

[Robstei]

I wanted to make sure that a used key is set in for all language files.

A solution I found is to use SharedUnionFieldsDeep from type-fest.

Is there a recommended way to do this or is there there any reason not do this?

// globals.ts
import type { SharedUnionFieldsDeep } from "type-fest";
import type germanMessages from "./messages/de.json";
import type messages from "./messages/en.json";

type Messages = SharedUnionFieldsDeep<typeof messages | typeof germanMessages>;

declare module "next-intl" {
  interface AppConfig {
    // ...
    Messages: Messages;
  }
}

[amannn]

That’s definitely a cool solution! If you don’t mind installing another dependency, I can also recommend i18n-check.