Can't set the Operation's `Errors` in a group modifier

I've got something like this:

```go
internalApi := huma.NewGroup(api, "/internal")

requireUserAuthHandler := auth.CreateRequireUserAuthHandler(internalApi)
internalApi.UseSimpleModifier(func(op *huma.Operation) {
op.Tags = append(op.Tags, "Internal")
if _, noAuth := op.Metadata["NoUserAuth"]; !noAuth {
op.Security = append(op.Security, map[string][]string{"SessionCookie": {}})
op.Middlewares = append(op.Middlewares, auth.UserAuthHandler, requireUserAuthHandler)
op.Errors = append(op.Errors, http.StatusUnauthorized)
}
})

sessionApi := huma.NewGroup(internalApi, "/session")
// a bunch of calls to huma.Register(sessionApi, ...)
```

When I specify `Errors` in the `Operation` passed to `huma.Register`, it's correctly defined in the OpenAPI document. But, it doesn't reflect the error codes updated by the simple modifier. The changes in the modifier to `Middlewares`, `Security`, and `Tags` are reflected correctly by the OpenAPI document, only changes to `Errors` are not reflected in the document.