"An error has occured" selection clause

[bhornerETHZ]

Working in the BD lecture cheatsheet 2023 HS' ipynb on the github dataset, I came across an error that I was told to report.

count(distinct-values(json-file("git-archive.json", 10).payload[$$.head eq $$[0].sha]))

Background: I wanted to find the number of events for which the payload head equals to the SHA of the first commit in the payload.

[ghislainfourny]

Thank @bhornerETHZ for the feedback. Indeed the [0] seems to lead to an error. JSONiq starts counting at 1, however there should not be an error, it should just silently return an empty sequence.