Function validate_client_path_transport 

pub fn validate_client_path_transport(
    parameters: &[KeyValuePair],
    over_webtransport: bool,
) -> Result<(), SetupError>

Refuse a PATH parameter on a session that is not native QUIC.

The same sentence in Section 9.3.1.2 forbids PATH “when WebTransport is used” and closes the session with INVALID_PATH on one received there. Which transport carries the session is known to the connection and not to the endpoint, so this is a separate call rather than part of validate_client_setup.

Errors

SetupError::PathOverWebTransport if a PATH is offered over WebTransport.