useCookies check for Provider doesn't work

[rstepinski]

The useCookies hook contains a check for a wrapping Provider:

const cookies = useContext(CookiesContext);
if (!cookies) {
  throw new Error('Missing <CookiesProvider>');
}

Unfortunately, this never throws because CookiesContext has a default value, therefore cookies is always defined and the condition is always false:

const CookiesContext = React.createContext(new Cookies());

This ended up biting me with some hydration errors which were pretty hard to track down, and indeed I just forgot to wrap my layout with CookiesProvider.