refactor(tracer): log warning instead of throwing when segment is not found

[dreamorosi]

Description of your changes

As reported in #1356, the current behavior of the Tracer and corresponding middleware is fairly unforgiving when it comes to handling missing segments. Prior to this PR, when calling the getSegment method, if a segment is not found, an error would be thrown.

This can happen either when users try to retrieve the current segment outside of the context of a function invocation or when the trace data is malformed and the X-Ray SDK is not able to derive the current segment.

This behavior, if not handled properly, can cause a function invocation to fail, which might not be desirable given that for many customers tracing is considered best-effort.

This PR:

• aligns the Tracer utility with the X-Ray SDK so that if a segment is not found, a warning is logged instead of throwing
• improves the handling of missing segments in the captureLambdaHandler middleware in all stages to be more resilient
• bumps the aws-xray-sdk-node dependency to the latest version
• refactor and extracts some of the internal logic around current segment retrieval from the Tracer class to the ProviderService one

This PR closes #1356.

How to verify this change

Check the existing tests as well as the newly added ones in the checks under this repo. Check also the results of this successful integration test.

Related issues, RFCs

Issue number: #1356

Checklist

• My changes meet the tenets criteria
• I have performed a self-review of my own code
• I have commented my code where necessary, particularly in areas that should be flagged with a TODO, or hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding changes to the examples
• My changes generate no new warnings
• The code coverage hasn't decreased
• I have added tests that prove my change is effective and works
• New and existing unit tests pass locally and in Github Actions
• Any dependent changes have been merged and published
• The PR title follows the conventional commit semantics

Breaking change checklist

Is it a breaking change?: NO

• I have documented the migration process
• I have added, implemented necessary warnings (if it can live side by side)

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

Disclaimer: We value your time and bandwidth. As such, any pull requests created on non-triaged issues might not be successful.

[am29d]

I like the cleanup it tests 👌, much easier to follow now.

The implications of additional undefined are bigger than I thought. It tears through many methods, similar to isTracingEnabled and reminds me of java or golang null checks. But I have no immediate answer to make it cleaner.

[dreamorosi]

I like the cleanup it tests 👌, much easier to follow now.

Thanks!

The implications of additional undefined are bigger than I thought. It tears through many methods, similar to isTracingEnabled and reminds me of java or golang null checks. But I have no immediate answer to make it cleaner.

Indeed, my attempt at somewhat centralising this behavior was to extract it in the provider class. This is also something I've been meaning to do for a while as it'd help decouple the two and open the door for other providers in the future.