Unable to determine event source based for running an async lambda function

Dear Reader,

I have gotten the following error when trying to configure a function to run async, running it sync does work.

Any ideas why this is happening?

```
{
"errorType": "Error",
"errorMessage": "Unable to determine event source based on event.",
"stack": [
"Error: Unable to determine event source based on event.",
" at getEventSourceNameBasedOnEvent (/var/task/node_modules/@vendia/serverless-express/src/event-sources/utils.js:79:9)",
" at proxy (/var/task/node_modules/@vendia/serverless-express/src/configure.js:37:51)",
" at Runtime.handler (/var/task/node_modules/@vendia/serverless-express/src/configure.js:95:12)",
" at Runtime.handleOnce (/var/runtime/Runtime.js:66:25)"
]
}
```

Start with getEventSourceNameBasedOnEvent in src/event-sources/utils.js, then follow its call from proxy in src/configure.js. Reproduce the failure with the async Lambda event and compare it with the working synchronous invocation. Done means identifying the unsupported or unexpected event shape and documenting a confirmed configuration or code-level resolution.

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