doc: improve documentation for util.types.isNativeError()

doc/api/util.md

@@ -2515,12 +2515,44 @@ added: v10.0.0
 * `value` {any}
 * Returns: {boolean}
 
-Returns `true` if the value is an instance of a built-in [`Error`][] type.
+Returns `true` if the value was returned by the constructor of a
+[built-in `Error` type][].
 
 ```js
-util.types.isNativeError(new Error());  // Returns true
-util.types.isNativeError(new TypeError());  // Returns true
-util.types.isNativeError(new RangeError());  // Returns true
+console.log(util.types.isNativeError(new Error()));  // true
+console.log(util.types.isNativeError(new TypeError()));  // true
+console.log(util.types.isNativeError(new RangeError()));  // true
+```
+
+Subclasses of the native error types will use the return value of the native
+error constructor as the new `this` and are therefore also native errors:
+
+```js
+class MyError extends Error {}
+console.log(util.types.isNativeError(new MyError()));  // true
+```
+
+A value being `instanceof` a native error class is not equivalent to `isNativeError()`
+returning `true` for that value. `isNativeError()` returns `true` for errors
+which come from a different [realm][] while `instanceof Error` returns `false`
+for these errors:
+
+```js
+const vm = require('node:vm');
+const context = vm.createContext({});
+const myError = vm.runInContext('new Error', context);
+console.log(util.types.isNativeError(myError)); // true
+console.log(myError instanceof Error); // false
+```
+
+Conversely, `isNativeError()` returns `false` for all objects which where not
+returned by the constructor of a native error. That includes values
+which are `instanceof` native errors:
+
+```js
+const myError = { __proto__: Error.prototype };
+console.log(util.types.isNativeError(myError)); // false
+console.log(myError instanceof Error)); // true
 ```
 
 ### `util.types.isNumberObject(value)`
@@ -3287,6 +3319,8 @@ util.log('Timestamped message.');
 [Customizing `util.inspect` colors]: #customizing-utilinspect-colors
 [Internationalization]: intl.md
 [Module Namespace Object]: https://tc39.github.io/ecma262/#sec-module-namespace-exotic-objects
+[realm]: https://tc39.es/ecma262/#realm
+[built-in `Error` type]: https://tc39.es/ecma262/#sec-error-objects
 [WHATWG Encoding Standard]: https://encoding.spec.whatwg.org/
 [`'uncaughtException'`]: process.md#event-uncaughtexception
 [`'warning'`]: process.md#event-warning