From 78e118c876172c970f678b3adff8987167fbed5f Mon Sep 17 00:00:00 2001
From: Sidharth Vinod <sidharthv96@gmail.com>
Date: Fri, 24 Nov 2023 09:42:21 +0530
Subject: [PATCH] fix: #5064 Handle case when line has only one point

---
 cypress/integration/rendering/flowchart-v2.spec.js | 12 ++++++++++++
 packages/mermaid/src/utils/lineWithOffset.ts       |  3 +++
 2 files changed, 15 insertions(+)

diff --git a/cypress/integration/rendering/flowchart-v2.spec.js b/cypress/integration/rendering/flowchart-v2.spec.js
index aac4a31b1..b7583ccf1 100644
--- a/cypress/integration/rendering/flowchart-v2.spec.js
+++ b/cypress/integration/rendering/flowchart-v2.spec.js
@@ -729,6 +729,18 @@ A ~~~ B
       {}
     );
   });
+
+  it('5064: Should render when subgraph child has links to outside node and subgraph', () => {
+    imgSnapshotTest(
+      `flowchart TB
+    Out --> In
+    subgraph Sub
+      In
+    end
+    Sub --> In`
+    );
+  });
+
   describe('Markdown strings flowchart (#4220)', () => {
     describe('html labels', () => {
       it('With styling and classes', () => {
diff --git a/packages/mermaid/src/utils/lineWithOffset.ts b/packages/mermaid/src/utils/lineWithOffset.ts
index f348d3eb3..a90eb7835 100644
--- a/packages/mermaid/src/utils/lineWithOffset.ts
+++ b/packages/mermaid/src/utils/lineWithOffset.ts
@@ -24,6 +24,9 @@ function calculateDeltaAndAngle(
 ): { angle: number; deltaX: number; deltaY: number } {
   point1 = pointTransformer(point1);
   point2 = pointTransformer(point2);
+  if (point1 === undefined || point2 === undefined) {
+    return { angle: 0, deltaX: 0, deltaY: 0 };
+  }
   const [x1, y1] = [point1.x, point1.y];
   const [x2, y2] = [point2.x, point2.y];
   const deltaX = x2 - x1;