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)：
missing region in config
対処
関連リンク
Configuring region in Node.js AWS SDK - Stack Overflow
https://stackoverflow.com/questions/31039948/configuring-region-in-node-js-aws-sdk
Configuration Error: Missing Region in Config (AWS)
https://stackoverflow.com/questions/47009074/configuration-error-missing-region-in-config-aws
How to configure the region in the AWS js SDK?
https://stackoverflow.com/questions/45032362/how-to-configure-the-region-in-the-aws-js-sdk
AWSCognito Missing region in config error
https://stackoverflow.com/questions/31976202/awscognito-missing-region-in-config-error
AWS Cognito - ConfigError: Missing region in config for ...
https://stackoverflow.com/questions/34897688/aws-cognito-configerror-missing-region-in-config-for-ja・・・
nodejsのaws-sdkを使うときに `~/.aws/credentials` を使う方法 - Qiita
https://qiita.com/tamanugi/items/4e0bee33507174a1647e
Missing region in config when using Lambda and config file ・ Issue ...
https://github.com/aws/aws-sdk-js/issues/1921
DynamoDB.DocumentClient Missing region in config ・ Issue #710 ...
https://github.com/aws/aws-sdk-js/issues/710
ConfigError: Missing region in config ・ Issue #109 ・ aws-amplify ...
https://github.com/aws-amplify/amplify-cli/issues/109
Failure: Missing region in config ・ Issue #189 ・ dherault/serverless ...
https://github.com/dherault/serverless-offline/issues/189