ai-workflow-course/modules/24-assistive-agents/lab/sample-issue.md

Title: done command crashes on an empty list

When I run python3 cli.py done 0 right after a fresh checkout, before adding any tasks, it throws an IndexError and dumps a stack trace instead of a friendly message. Every other command handles the empty-list case fine, so this one feels like an oversight.

Steps to reproduce:

1. Delete tasks.json (or clone fresh).
2. Run python3 cli.py done 0.
3. See the traceback.

Expected: a clear message like "no task at index 0", exit non-zero, no traceback.

Environment: Python 3.12, macOS.