There was a missing rest field access. In addition createTag doesn't actually create a tag, it creates a tag object. A tag object is an object which references a commit or other kind of object and has various kinds of metadata. You need to store it in a reference stored in refs/tags/ to actually show as tag in the git ui. The code to update the tag however creates a lightweight tag (which is a file in refs/tags/ which directly references a commit rather than a tag object) as such do the same when creating the initial dev tag by using createRef with a commit id as object sha.
See also https://git-scm.com/book/en/v2/Git-Internals-Git-References for the difference between a lightweight tag and an annotated tag.
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