React Router v7 Framework mode, server side, optional route parameters

[michelbieleveld]

Hi, how would I detect whether a route has an optional parameter that is null vs not being defined. In other words, how can I detect if the route has an optional lang parameter ( file based routing):

($lang).dashboard.tsx
someother.tsx

I would expect:
/dashboard.tsx -> lang = null
/en/dashboard.tsx -> lang = en
/someother.tsx -> lang = undefined

It seems that the lang = null does not happen, it is just missing on params and hence undefined. (Or likely I am doing something wrong) I am trying to do this test in middleware.

The goal would be to redirect to a default language in case there is a language dependent version of that route. Open to other suggestions to solve this problem too.