From 1fd030972464b7aa9eb0812ca88d54a159261d0f Mon Sep 17 00:00:00 2001
From: Bojun Chai <bojunchai@microsoft.com>
Date: Tue, 21 Apr 2026 00:23:05 +0800
Subject: [PATCH] fix: validate non-numeric level options

---
 source/index.js  | 2 +-
 test/instance.js | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/source/index.js b/source/index.js
index 8bc993d..bbb0751 100644
--- a/source/index.js
+++ b/source/index.js
@@ -22,7 +22,7 @@ const levelMapping = [
 const styles = Object.create(null);
 
 const applyOptions = (object, options = {}) => {
-	if (options.level && !(Number.isInteger(options.level) && options.level >= 0 && options.level <= 3)) {
+	if (options.level !== undefined && !(Number.isInteger(options.level) && options.level >= 0 && options.level <= 3)) {
 		throw new Error('The `level` option should be an integer from 0 to 3');
 	}
 
diff --git a/test/instance.js b/test/instance.js
index c3cc70b..7a953f9 100644
--- a/test/instance.js
+++ b/test/instance.js
@@ -20,5 +20,13 @@ test('the `level` option should be a number from 0 to 3', t => {
 	t.throws(() => {
 		new Chalk({level: -1});
 	}, {message: /should be an integer from 0 to 3/});
+
+	t.throws(() => {
+		new Chalk({level: null});
+	}, {message: /should be an integer from 0 to 3/});
+
+	t.throws(() => {
+		new Chalk({level: Number.NaN});
+	}, {message: /should be an integer from 0 to 3/});
 	/* eslint-enable no-new */
 });