From 4697daf5bf1468ebad56387979c95c1b7e1bee34 Mon Sep 17 00:00:00 2001
From: cherenkov <chrnkv@gmail.com>
Date: Sun, 18 Oct 2026 08:07:03 +0900
Subject: [PATCH] Ensure blur reports the received value for invalid sigma

`sigma` was declared without an initial value, so validation errors for
`blur({ sigma: 'x' })` and `blur('5')` always reported
"received undefined of type undefined". Initialise `sigma` from
`options` and pass `options.sigma` when validating the object form.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 lib/operation.mjs |  8 +++-----
 test/unit/blur.js | 14 ++++++++++++++
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/lib/operation.mjs b/lib/operation.mjs
index d10aa8d00..5c788b46f 100644
--- a/lib/operation.mjs
+++ b/lib/operation.mjs
@@ -379,12 +379,10 @@ function median (size) {
  * @throws {Error} Invalid parameters
  */
 function blur (options) {
-  let sigma;
-  if (is.number(options)) {
-    sigma = options;
-  } else if (is.plainObject(options)) {
+  let sigma = options;
+  if (is.plainObject(options)) {
     if (!is.number(options.sigma)) {
-      throw is.invalidParameterError('options.sigma', 'number between 0.3 and 1000', sigma);
+      throw is.invalidParameterError('options.sigma', 'number between 0.3 and 1000', options.sigma);
     }
     sigma = options.sigma;
     if ('precision' in options) {
diff --git a/test/unit/blur.js b/test/unit/blur.js
index 13f010124..dfddea94e 100644
--- a/test/unit/blur.js
+++ b/test/unit/blur.js
@@ -151,4 +151,18 @@ suite('Blur', () => {
       sharp(fixtures.inputJpg).blur({ precision: 'invalid' });
     }, /Expected number between 0.3 and 1000 for options.sigma but received undefined of type undefined/);
   });
+
+  test('invalid options.sigma', (t) => {
+    t.plan(1);
+    t.assert.throws(() => {
+      sharp(fixtures.inputJpg).blur({ sigma: 'x' });
+    }, /Expected number between 0.3 and 1000 for options.sigma but received x of type string/);
+  });
+
+  test('invalid sigma', (t) => {
+    t.plan(1);
+    t.assert.throws(() => {
+      sharp(fixtures.inputJpg).blur('5');
+    }, /Expected number between 0.3 and 1000 for sigma but received 5 of type string/);
+  });
 });