From e0ad4de5aac7a7034783bc2332e61cd47e48ab4e Mon Sep 17 00:00:00 2001
From: David Newell <davidnewell@google.com>
Date: Wed, 13 Mar 2024 14:34:51 +0000
Subject: [PATCH] Checking for empty layers before checking for conflicts

---
 lib/order/index.js | 2 ++
 lib/position/bk.js | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/order/index.js b/lib/order/index.js
index 9259f170..504ce11e 100644
--- a/lib/order/index.js
+++ b/lib/order/index.js
@@ -38,6 +38,7 @@ function order(g, opts) {
   let maxRank = util.maxRank(g),
     downLayerGraphs = buildLayerGraphs(g, util.range(1, maxRank + 1), "inEdges"),
     upLayerGraphs = buildLayerGraphs(g, util.range(maxRank - 1, -1, -1), "outEdges");
+
   let layering = (0, _initOrder.default)(g);
   assignOrder(g, layering);
 
@@ -47,6 +48,7 @@ function order(g, opts) {
 
   let bestCC = Number.POSITIVE_INFINITY,
     best;
+
   for (let i = 0, lastBest = 0; lastBest < 4; ++i, ++lastBest) {
     sweepLayerGraphs(i % 2 ? downLayerGraphs : upLayerGraphs, i % 4 >= 2);
     layering = util.buildLayerMatrix(g);
diff --git a/lib/position/bk.js b/lib/position/bk.js
index f4436c6b..5283b009 100644
--- a/lib/position/bk.js
+++ b/lib/position/bk.js
@@ -70,7 +70,7 @@ function findType1Conflicts(g, layering) {
     });
     return layer;
   }
-  layering.reduce(visitLayer);
+  layering.length && layering.reduce(visitLayer);
   return conflicts;
 }
 function findType2Conflicts(g, layering) {
@@ -107,7 +107,7 @@ function findType2Conflicts(g, layering) {
     });
     return south;
   }
-  layering.reduce(visitLayer);
+  layering.length && layering.reduce(visitLayer);
   return conflicts;
 }
 function findOtherInnerSegmentNode(g, v) {