From c5ecd2c33d56d220ee79e667392b65ab313b99ed Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philippe=20Rivi=C3=A8re?= <fil@rezo.net>
Date: Wed, 18 Mar 2026 10:04:09 +0100
Subject: [PATCH] throw Error: invalid dodge radius: -1 instead of crashing
 with a stack overflow.

closes #1912
---
 src/transforms/dodge.js       |  1 +
 test/transforms/dodge-test.ts | 12 ++++++++++++
 2 files changed, 13 insertions(+)
 create mode 100644 test/transforms/dodge-test.ts

diff --git a/src/transforms/dodge.js b/src/transforms/dodge.js
index 23c20bd807..5dcaa499e3 100644
--- a/src/transforms/dodge.js
+++ b/src/transforms/dodge.js
@@ -71,6 +71,7 @@ function dodge(y, x, anchor, padding, r, options) {
     if (!channels[x]) throw new Error(`missing channel: ${x}`);
     ({[x]: X} = applyPosition(channels, scales, context));
     const cr = R ? undefined : r !== undefined ? number(r) : this.r !== undefined ? this.r : 3;
+    if (cr !== undefined && !(cr > 0)) throw new Error(`invalid dodge radius: ${cr}`);
     if (R) R = valueof(R.value, scales[R.scale] || identity, Float64Array);
     let [ky, ty] = anchor(dimensions);
     const compare = ky ? compareAscending : compareSymmetric;
diff --git a/test/transforms/dodge-test.ts b/test/transforms/dodge-test.ts
new file mode 100644
index 0000000000..07e14fc0d1
--- /dev/null
+++ b/test/transforms/dodge-test.ts
@@ -0,0 +1,12 @@
+import * as Plot from "@observablehq/plot";
+import assert from "assert";
+import it from "../jsdom.js";
+
+it("dodgeY throws on non-positive constant r", () => {
+  assert.throws(() => Plot.dot([1, 2, 3], Plot.dodgeY({x: Plot.identity, r: -1})).plot(), /invalid dodge radius/);
+  assert.throws(() => Plot.dot([1, 2, 3], Plot.dodgeY({x: Plot.identity, r: 0})).plot(), /invalid dodge radius/);
+});
+
+it("dodgeX throws on non-positive constant r", () => {
+  assert.throws(() => Plot.dot([1, 2, 3], Plot.dodgeX({y: Plot.identity, r: -1})).plot(), /invalid dodge radius/);
+});