diff --git a/actions/setup/js/memory_custom_validation.cjs b/actions/setup/js/memory_custom_validation.cjs
index a92f4cc67fc..58099ac7fe2 100644
--- a/actions/setup/js/memory_custom_validation.cjs
+++ b/actions/setup/js/memory_custom_validation.cjs
@@ -45,12 +45,12 @@ function readDirectory(targetPath) {
 
 /**
  * @param {string} targetPath
- * @param {BufferEncoding | undefined} [encoding]
+ * @param {BufferEncoding} [encoding]
  * @returns {any}
  */
 function readFile(targetPath, encoding) {
   try {
-    return fs.readFileSync(targetPath, encoding);
+    return encoding ? fs.readFileSync(targetPath, encoding) : fs.readFileSync(targetPath);
   } catch (error) {
     throw new Error(`Failed to read ${targetPath}: ${getErrorMessage(error)}`, { cause: error });
   }
diff --git a/actions/setup/js/package-lock.json b/actions/setup/js/package-lock.json
index 53fe92f7cbb..f2cf2dff641 100644
--- a/actions/setup/js/package-lock.json
+++ b/actions/setup/js/package-lock.json
@@ -13,7 +13,7 @@
         "@actions/glob": "^0.7.0",
         "@actions/io": "^3.0.2",
         "@github/copilot-sdk": "^1.0.11",
-        "@types/node": "^26.2.0",
+        "@types/node": "^26.4.0",
         "@vitest/coverage-v8": "^4.1.11",
         "@vitest/ui": "^4.1.10",
         "minimatch": ">=10.2.6",
@@ -1587,9 +1587,9 @@
       "license": "MIT"
     },
     "node_modules/@types/node": {
-      "version": "26.2.0",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-26.2.0.tgz",
-      "integrity": "sha512-5IviulTZeRNp2vAJ514cc/HUlY5nZ9fCbq9DMyC52BrhFZACo3nI0R7qBxhQmo/d27NFe96ur/b7Wwxklda+kg==",
+      "version": "26.4.0",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-26.4.0.tgz",
+      "integrity": "sha512-faiGnoIrLH/V8cibOMEAZ8pMw6oXqSukl29ra4mN8GdaB2ZewzeaLj+INpV5N+Z1eKWzY+IzaIZH2EIR6YZRNQ==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
diff --git a/actions/setup/js/package.json b/actions/setup/js/package.json
index 6f563dcf801..6995e7ec467 100644
--- a/actions/setup/js/package.json
+++ b/actions/setup/js/package.json
@@ -8,7 +8,7 @@
     "@actions/glob": "^0.7.0",
     "@actions/io": "^3.0.2",
     "@github/copilot-sdk": "^1.0.11",
-    "@types/node": "^26.2.0",
+    "@types/node": "^26.4.0",
     "@vitest/coverage-v8": "^4.1.11",
     "@vitest/ui": "^4.1.10",
     "minimatch": ">=10.2.6",