Unrecognised relations in Content-Type interferes with content negotiation

curl -iH'Accept: application/ld+json' https://csarven.solid.community/public/
HTTP/1.1 200 OK
Content-Type: application/ld+json

curl -iH'Accept: application/ld+json; profile="https://www.w3.org/ns/activitystreams"' https://csarven.solid.community/public/
HTTP/1.1 200 OK
Content-Type: text/turtle

See also:

curl -iH'Accept: application/ld+json; profile=""' https://csarven.solid.community/public/
Content-Type: application/ld+json

curl -iH'Accept: application/ld+json; profile="x"' https://csarven.solid.community/public/
Content-Type: text/turtle

curl -iH'Accept: application/ld+json; x=""' https://csarven.solid.community/public/
Content-Type: application/ld+json

curl -iH'Accept: application/ld+json; x="y"' https://csarven.solid.community/public/
Content-Type: text/turtle

The server should at the very least ignore the relations it can't handle and return application/ld+json, or return 406.

Start by running the curl examples against the server and compare content negotiation for unsupported and empty media-type parameters. Trace the request handling that selects the response representation; done means unsupported relations are ignored with application/ld+json returned, or the request receives 406.