improve

packages/common/src/models/lang.ts

@@ -0,0 +1,6 @@
+export const SUPPORTED_LANGS = ["fr", "en"];
+export type SupportedLangs = (typeof SUPPORTED_LANGS)[number];
+
+export function isSupportedLang(obj: unknown): obj is SupportedLangs {
+  return (SUPPORTED_LANGS as unknown[]).includes(obj);
+}