Smart error messages

[shoo]

If a compilation error occurs in the STM that imported with string import and converted to code, an error message that is difficult to read is reported.
Indicating which error occurred in what row and column of which STM greatly contributes to the ease of debugging.

Related to: #1

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string importで取り込み、コードへ変換した状態遷移表の中でエラーが発生した場合、きわめて難読なエラーメッセージが報じられます。
どの状態遷移表の、何行何列目でエラーが生じたかを示すことは、デバッグのしやすさに大きく寄与します。

[shoo]

By the way, by adding dflags: ["-mixin=.dub/my_mixin.d"] to dub.json, the importance of this issue has become less important, as it is almost clear where it is going wrong.

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ところで、dub.jsonに dflags: ["-mixin=.dub/my_mixin.d"] と追記することで、どこでおかしくなっているかだいたいわかるので、このIssueの重要性は低くなりましたね。