If the user email exists, then return the user. Otherwise return null if there is no invite.
This way we can lock down the "apps/{app_name}/users" collection read access to require authentication. So in addition to creating this new function, we need to update the firestore rules.
If the user email exists, then return the user. Otherwise return null if there is no invite.
This way we can lock down the "apps/{app_name}/users" collection read access to require authentication. So in addition to creating this new function, we need to update the firestore rules.