From @jeff-zucker in gitter:

It seems to me that if they enter something, you try to login to it and if you are successful, you retrieve the webid info from the login response and grab whatever you need from the profile; if your attempt to login was unsuccessful, you assume what they have entered is a WebID and you try to open that as a profile, retrieve the solid:oidcIssuer from there and login with that. I don't see that having a predicate identifying the profile would be helpful in that flow. Suppose they enter something that is neither an login endpoint nor a profile document - you would know that because it doesn't have a solid:oidcIssuer or other predicate you need from the profile - you could then try various things to guess the IdP or the WebID, although the guessing process is not guaranteed to turn up anything useful. The relevant question is not "is this a profile document", but rather "does this have the predicates I need to use and expect to find in a profile document.

Usage of @types/rdf-js should be @rdfjs/types instead. See https://github.com/rdfjs/types?tab=readme-ov-file#what-about-typesrdf-js

This was discovered in the same way as jacoscaz/quadstore#167 (comment).