Structured error display

I had an exception, and I was in devtools, and it would have been super useful to be able to inspect the various objects mentioned in the structured error message.

Especially useful would have been the ability to inspect the properties of the objects, and be able to jump to the corresponding render objects in the inspector view.

This is probably a medium-priority feature request. In particular, if we don't have this feature, it draws into question why we bother having structured error messages at all; if the feature is no longer deemed useful, we should simplify the framework code by removing all the logic around structured errors.

まず、DevTools が構造化されたエラーメッセージをどのように表示し、インスペクタービューが render objects をどのように表現しているかを追跡します。オブジェクトのプロパティと対応する render objects を検査できるように公開する方法を判断します。構造化されたエラーが既存の目的を失うことなく両方の機能をサポートすれば完了です。

索引モデルが issue の本文から書いたものです。