Good catch: I’ve written many thousands of lines of shell scripts over the years and that’s exactly the kind of rake in the grass which is too easy to miss. Using set -eu -o PIPEFAIL helps as does shellcheck but it’s still easier than it should be to have unexpected behavior from something you thought was well tested.

About 15 years ago I switched to Python for anything which doesn’t fit on a single screen or uses any advanced feature and have had zero reasons to regret that decision. It’s especially good for anything you use with other people since you spend your time talking about features rather than how to trick the shell into working correctly.