The author of the text uses Lumigo, a tool that records context about each Lambda invocation, including environment variables, to debug an error in a client project. The error occurred after a deployment and was initially suspected to be related to code changes rather than environmental changes. By comparing snapshots of environment variables using Lumigo, the author quickly identified that the issue was caused by a change in the SSM parameter value used to share infrastructure configuration between services. This allowed them to identify the root cause of the problem and resolve it quickly, highlighting the benefits of using Lumigo for debugging purposes.