"Cannot find module" message should be more explicit, saying where it's looking

With all the vagaries around module loading, it'd be great to give a more verbose, helpful error message for "Cannot find module 'foo'", saying where the compiler looked for the module. That can help clue the user into (1) how TypeScript works and (2) how to fix their issue.

The message text could be semi-static, maybe something like: IF using commonjs loading AND path isn't relative THEN say "Couldn't find module Foo; searched node_modules directory off directory XXXX and its ancestors and the package.json Typings path YYYY.

Better doc around the module loading algorithm helps, but just putting some of that info in the error message makes it very easily discovered. It also helps clue the user into what isn't the problem (e.g. the message above confirms that using commonjs module loading & found Typings in package.json, but something else seems to be the problem).

まず、CommonJS モジュールの読み込み、祖先ディレクトリでの node_modules の検索、package.json の Typings パスについて記述された issue の説明を読みます。コンパイラーのモジュール解決と診断のエントリポイントを追跡し、次に "Cannot find module" エラーに対する既存のテストを特定します。解決時にどこを検索したかを診断が説明し、元の失敗を不明瞭にしなければ完了です。