it is not finding the password used for encrypting the user session, in your case is the VITE_SESSION_SECRET environment variable, is it set in your .env file?
Cloud Flare Context is not defined when using Session
I refactored the code a bit, based on the "with-auth" template
it is probably a Cloud Flare Wrangler issue since on node-server preset it works as expected
the erros happens when trying to call login or logout
here it is some code