refactor: Allow for client identities with no user ID

src/api/client/read_marker.rs

@@ -26,7 +26,7 @@ pub(crate) async fn set_read_marker_route(
 	State(services): State<crate::State>,
 	body: Ruma<set_read_marker::v3::Request>,
 ) -> Result<set_read_marker::v3::Response> {
-	let sender_user = body.identity.sender_user();
+	let sender_user = body.identity.expect_sender_user()?;
 
 	if let Some(event) = &body.fully_read {
 		let fully_read_event = FullyReadEvent::new(FullyReadEventContent::new(event.to_owned()));
@@ -118,7 +118,8 @@ pub(crate) async fn create_receipt_route(
 	ClientIp(client_ip): ClientIp,
 	body: Ruma<create_receipt::v3::Request>,
 ) -> Result<create_receipt::v3::Response> {
-	let sender_user = body.identity.sender_user();
+	let sender_user = body.identity.expect_sender_user()?;
+
 	services
 		.users
 		.update_device_last_seen(sender_user, body.identity.sender_device(), client_ip)