In the test the argument reference "Z10043K1" refers to itself: https://github.com/wikimedia/mediawiki-services-function-orchestrator/blob/1493b87952b0dad72426c80026ce8e9d091abdae/test/features/v1/test_data/map-Z10043.json#L132.
This should normally not be allowed. Currently passes because of dynamic scoping (https://phabricator.wikimedia.org/T309038), and so blocks the fix for that bug.