Function validate_client_path_transport 

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

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

The same sentence in Section 10.3.1.2 forbids PATH “when WebTransport is used”. Which transport carries the session is known to the connection and not to the endpoint, so this is a separate call.

Errors

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