Log error location

resolves #1619

So that we can see the context of an error in Cloudwatch logs, I have added an errorLocation key to the errorFormatted data structure. This means that the file and line number where the exception is thrown is logged.

Any feedback on this appreciated @mnapoli

I'm sorry, while reviewing this I'm realizing this object follows a structure defined by AWS Lambda: https://docs.aws.amazon.com/lambda/latest/dg/runtimes-api.html#runtimes-api-invokeerror

I apologize for not spotting that sooner 🤦

I'm thinking of 3 options:

1. adding the extra errorLocation (current state of the PR) if it doesn't break error reporting and that new field shows up in the CloudWatch logs
2. adding the file + line in the stack trace (insert it as the first line?
3. adding the file + line to the error message

For reference, here's what PHP logs in case of an uncaught exception:

Note: I don't think it's a good reference though because it's an "Uncaught exception" line that is a fatal error. In our case it's not exactly that, exceptions are OK (to communicate errors to Lambda), so we don't necessarily want to copy that format.

I think the 1st option is the best, but that requires testing on Lambda to confirm the behavior works as expected.

Closing inactive PRs, feel free to reopen.