simple express api calling external end point through fetch failing with TypeError: o is not a function

Hi
I followed examples/basic-starter-api-gateway-v1 setup and updated app.js to include a new endpoint definition that uses fetch to call an external end point , external rest endpoint implemented within express returns a json response ( verified through postman ). However the fetch call is throwing this error ( zip of the root folder that includes my app.js is attached
[my-serverless-express.zip](https://github.com/vendia/serverless-express/files/6713379/my-serverless-express.zip)
)
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2021-06-24T04:30:31.822Z aa7e4631-258c-4ed2-9ae0-b410af797e86 INFO TypeError: o is not a function
at fn (/var/task/webpack:/@vendia/serverless-express-example/src/app.js:102:28)
at r.handle_request (/var/task/webpack:/@vendia/serverless-express-example/node_modules/express/lib/router/layer.js:95:5)
at next (/var/task/webpack:/@vendia/serverless-express-example/node_modules/express/lib/router/route.js:137:13)
at p.fn [as dispatch] (/var/task/webpack:/@vendia/serverless-express-example/node_modules/express/lib/router/route.js:112:3)
at r.handle_request (/var/task/webpack:/@vendia/serverless-express-example/node_modules/express/lib/router/layer.js:95:5)
at done (/var/task/webpack:/@vendia/serverless-express-example/node_modules/express/lib/router/index.js:281:22)
at Function.process_params (/var/task/webpack:/@vendia/serverless-express-example/node_modules/express/lib/router/index.js:335:12)
at next (/var/task/webpack:/@vendia/serverless-express-example/node_modules/express/lib/router/index.js:275:10)
at fn (/var/task/webpack:/@vendia/serverless-express-example/node_modules/express/lib/middleware/init.js:40:5)
at r.handle_request (/var/task/webpack:/@vendia/serverless-express-example/node_modules/express/lib/router/layer.js:95:5)
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examples/basic-starter-api-gateway-v1 と添付された app.js を調査し、特に stack trace に示されている 102 行目の endpoint を確認してください。Postman で検証された Express endpoint と比較し、外部の fetch 呼び出しで TypeError が発生する理由を追跡してください。fetch を使用する route が正常に実行され、期待される JSON レスポンスを返せば完了です。

索引モデルが issue の本文から書いたものです。