util.inspect() on Errors does not include stack trace

`util.inspect(new Error('foo'))` in Node prints the stack trace of the error:
```
Error: foo
at repl:1:15
at Script.runInThisContext (vm.js:122:20)
at REPLServer.defaultEval (repl.js:334:29)
at bound (domain.js:395:14)
at REPLServer.runBound [as eval] (domain.js:408:12)
at REPLServer.onLine (repl.js:641:10)
at REPLServer.emit (events.js:187:15)
at REPLServer.EventEmitter.emit (domain.js:441:20)
at REPLServer.Interface._onLine (readline.js:301:10)
at REPLServer.Interface._line (readline.js:673:8)
```
This shim however just returns
```
[Error: foo]
```
Which is really bad if this is used as part of a logging tool.

Locate the util.inspect() implementation and its handling of Error objects, then compare the shim's output with Node's output shown in the issue. Confirm that inspecting an Error includes its stack trace while preserving the expected message formatting.

索引モデルが issue の本文から書いたものです。