f: alternative (more legible?) approach for older Rust version CI fixes for the façade method

Author: arik-so

lightning/src/ln/onion_utils.rs

@@ -949,25 +949,29 @@ where
 		_ => unreachable!(),
 	};
 
-	let secondary_session_priv = path.has_trampoline_hops().then(|| {
+	if path.has_trampoline_hops() {
 		// If we have Trampoline hops, the outer onion session_priv is a hash of the inner one.
 		let session_priv_hash = Sha256::hash(&primary_session_priv.secret_bytes()).to_byte_array();
-		SecretKey::from_slice(&session_priv_hash[..]).expect("You broke SHA-256!")
-	});
-
-	// the outer onion's session priv is the secondary (if it's set), or the primary as its fallback
-	let outer_session_priv = secondary_session_priv.as_ref().unwrap_or(primary_session_priv);
-	// the inner onion's session priv is only set if there is a secondary
-	let inner_session_priv = secondary_session_priv.as_ref().map(|_| primary_session_priv);
-
-	process_onion_failure_inner(
-		secp_ctx,
-		logger,
-		htlc_source,
-		outer_session_priv,
-		inner_session_priv,
-		encrypted_packet,
-	)
+		let outer_session_priv =
+			SecretKey::from_slice(&session_priv_hash[..]).expect("You broke SHA-256!");
+		process_onion_failure_inner(
+			secp_ctx,
+			logger,
+			htlc_source,
+			&outer_session_priv,
+			Some(primary_session_priv),
+			encrypted_packet,
+		)
+	} else {
+		process_onion_failure_inner(
+			secp_ctx,
+			logger,
+			htlc_source,
+			primary_session_priv,
+			None,
+			encrypted_packet,
+		)
+	}
 }
 
 /// Process failure we got back from upstream on a payment we sent (implying htlc_source is an