このエラーメッセージに関する原因と対処に関して説明します。
エラーメッセージ(英語)：
object has no index signature
対処
関連リンク
Enum to String Lookup Object -> has no index Signature - Stack ...stackoverflow.com/.../enum-to-string-lookup-object-has...
https://stackoverflow.com/questions/46353697/enum-to-string-lookup-object-has-no-index-signature
Typescript: what could be causing this error ...
https://stackoverflow.com/questions/41929287/typescript-what-could-be-causing-this-error-element-imp・・・
How to access a property of an object using the ...
https://stackoverflow.com/questions/55959262/how-to-access-a-property-of-an-object-using-the-bracket・・・