The `access.read` function executed within form state was missing the
`id` arg, and was also incorrectly setting `data` as `doc`. When
building form state, there is no concept of a "doc" because it is
possible to build form state using only a subset of fields. There is
"data", however, which represents the schema path at the entry point of
the function. Similarly, when building form state on within an
`onChange` function, for example, we do not send the original doc
through the request, which is what "doc" would represent. Instead, we
send either `data` or `formState`, both of which could represent a
_modified_ doc. This particular invocation of read access does not
effect the visibility of fields themselves, but rather their return
values from the form state endpoint. Field visibility is determined at
the request level.
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