Typesafety: prevent usage of non existing keys

[ThomasKientz]

Clear and concise description of the problem

We can setup autocompletion with typescript but we can't make typescript throws an error if we try to translate a non existing key.

import type fr from "../i18n/fr.json";
const { t } = useI18n<{ message: typeof fr }>();

const translation = t("key.non_existing"); // doesn't throw a typescript error

Suggested solution

Update the types to make typescript throws an error.

Alternative

Adding <""> makes typescript throws:

import type fr from "../i18n/fr.json";
const { t } = useI18n<{ message: typeof fr }>();

const translation = t<"">("key.non_existing"); // ts throws error as exepected

Additional context

No response

Validations

• Read the Contributing Guidelines
• Read the Documentation
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.