Plumber won't simply exit when reading from SQS, kill -9 is required

[przemek-pokrywka]

Describe the bug
Plumber reads from the SQS queue but doesn't exit; I must force kill it.

To Reproduce
Steps to reproduce the behavior:

1. Ensure that my-queue SQS queue exists and is readable to your AWS user
2. Execute: plumber read aws-sqs --quiet --json --receive-request-attempt-id=1765291115 --max-num-messages=10 --sample-interval-seconds=5 --queue-name=my-queue

Expected behavior
I expected to see the messages from the queue and the plumber process graceful exit, code zero.

CLI (please complete the following information):

• OS: Darwin REDACTED.local 24.6.0 Darwin Kernel Version 24.6.0: Wed Oct 15 21:12:15 PDT 2025; root:xnu-11417.140.69.703.14~1/RELEASE_ARM64_T6041 arm64 arm Darwin
• Version [e.g. 2.9.0]

Additional context
When I do a regular kill, I get:

INFO[0023] Shutting down plumber...

but nothing happens (plumber hangs) until I do kill -9