util: fix error's namespaced node_modules highlighting using inspect

lib/internal/util/inspect.js

@@ -244,7 +244,6 @@ const keyStrRegExp = /^[a-zA-Z_][a-zA-Z_0-9]*$/;
 const numberRegExp = /^(0|[1-9][0-9]*)$/;
 
 const coreModuleRegExp = /^ {4}at (?:[^/\\(]+ \(|)node:(.+):\d+:\d+\)?$/;
-const nodeModulesRegExp = /[/\\]node_modules[/\\](.+?)(?=[/\\])/g;
 
 const classRegExp = /^(\s+[^(]*?)\s*{/;
 // eslint-disable-next-line node-core/no-unescaped-regexp-dot
@@ -1412,16 +1411,45 @@ function removeDuplicateErrorKeys(ctx, keys, err, stack) {
 
 function markNodeModules(ctx, line) {
   let tempLine = '';
-  let nodeModule;
-  let pos = 0;
-  while ((nodeModule = nodeModulesRegExp.exec(line)) !== null) {
-    // '/node_modules/'.length === 14
-    tempLine += StringPrototypeSlice(line, pos, nodeModule.index + 14);
-    tempLine += ctx.stylize(nodeModule[1], 'module');
-    pos = nodeModule.index + nodeModule[0].length;
-  }
-  if (pos !== 0) {
-    line = tempLine + StringPrototypeSlice(line, pos);
+  let lastPos = 0;
+  let searchFrom = 0;
+
+  while (true) {
+    const nodeModulePosition = StringPrototypeIndexOf(line, 'node_modules', searchFrom);
+    if (nodeModulePosition === -1) {
+      break;
+    }
+
+    // Ensure it's a path segment: must have a path separator before and after
+    const separator = line[nodeModulePosition - 1];
+    const after = line[nodeModulePosition + 12]; // 'node_modules'.length === 12
+
+    if ((after !== '/' && after !== '\\') || (separator !== '/' && separator !== '\\')) {
+      // Not a proper segment; continue searching
+      searchFrom = nodeModulePosition + 1;
+      continue;
+    }
+
+    const moduleStart = nodeModulePosition + 13; // Include trailing separator
+
+    // Append up to and including '/node_modules/'
+    tempLine += StringPrototypeSlice(line, lastPos, moduleStart);
+
+    let moduleEnd = StringPrototypeIndexOf(line, separator, moduleStart);
+    if (line[moduleStart] === '@') {
+      // Namespaced modules have an extra slash: @namespace/package
+      moduleEnd = StringPrototypeIndexOf(line, separator, moduleEnd + 1);
+    }
+
+    const nodeModule = StringPrototypeSlice(line, moduleStart, moduleEnd);
+    tempLine += ctx.stylize(nodeModule, 'module');
+
+    lastPos = moduleEnd;
+    searchFrom = moduleEnd;
+  }
+
+  if (lastPos !== 0) {
+    line = tempLine + StringPrototypeSlice(line, lastPos);
   }
   return line;
 }

test/parallel/test-util-inspect.js

@@ -2837,7 +2837,7 @@ assert.strictEqual(
   // Use a fake stack to verify the expected colored outcome.
   const stack = [
     'Error: CWD is grayed out, even cwd that are percent encoded!',
-    '    at A.<anonymous> (/test/node_modules/foo/node_modules/bar/baz.js:2:7)',
+    '    at A.<anonymous> (/test/node_modules/foo/node_modules/@namespace/bar/baz.js:2:7)',
     '    at Module._compile (node:internal/modules/cjs/loader:827:30)',
     '    at Fancy (node:vm:697:32)',
     // This file is not an actual Node.js core file.
@@ -2862,7 +2862,7 @@ assert.strictEqual(
   }
   const escapedCWD = util.inspect(process.cwd()).slice(1, -1);
   util.inspect(err, { colors: true }).split('\n').forEach((line, i) => {
-    let expected = stack[i].replace(/node_modules\/([^/]+)/gi, (_, m) => {
+    let expected = stack[i].replace(/node_modules\/(@[^/]+\/[^/]+|[^/]+)/gi, (_, m) => {
       return `node_modules/\u001b[4m${m}\u001b[24m`;
     }).replaceAll(new RegExp(`(\\(?${escapedCWD}(\\\\|/))`, 'gi'), (_, m) => {
       return `\x1B[90m${m}\x1B[39m`;