Use `saturating_add` when adding inflight HTLCs values

Previously this calculation could overflow, leading to panicking in `debug`.

diff --git a/lightning/src/routing/router.rs b/lightning/src/routing/router.rs
index 09d83bb785cdfe1d9ac2786cce278311a6279648..0e3bc96ea00635a44becbda9f2d1bd3ff9c3bbe6 100644 (file)
--- a/lightning/src/routing/router.rs
+++ b/lightning/src/routing/router.rs
@@ -139,7 +139,7 @@ impl<'a, SP: Sized, Sc: 'a + ScoreLookUp<ScoreParams = SP>, S: Deref<Target = Sc
                        source, target, short_channel_id
                ) {
                        let usage = ChannelUsage {
-                               inflight_htlc_msat: usage.inflight_htlc_msat + used_liquidity,
+                               inflight_htlc_msat: usage.inflight_htlc_msat.saturating_add(used_liquidity),
                                ..usage
                        };