У нас есть специальная мода `ns-view-error-content` https://github.com/yandex-ui/noscript/blob/master/yate/noscript.yate#L93.

Я делаю, к примеру, так:
```html
match .photo[ /.errors.photo.name == 'image not found' ] ns-view-error-content {
    "Image was not found"
}
```