f - Use optional_vec in Writeable for ReceiveTlvs

Author: jkczyz

lightning/src/blinded_path/mod.rs

@@ -224,9 +224,12 @@ impl Writeable for ForwardTlvs {
 
 impl Writeable for ReceiveTlvs {
 	fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
+		const EMPTY_PATH_ID: &Vec<u8> = &vec![];
+		let path_id = self.path_id.as_ref().unwrap_or(EMPTY_PATH_ID);
+
 		// TODO: write padding
 		encode_tlv_stream!(writer, {
-			(6, self.path_id, (option, encoding: WithoutLength)),
+			(6, *path_id, optional_vec),
 		});
 		Ok(())
 	}