Summary:
While adding `FetchSelectedOptions` in 4e67c679b2, I accidentally made `viewApi` become an undocumented variable, which is fixed here.
While I was at it, I also fixed other errors emitted by `./build-plugin-api.sh`.
Test Plan: Built changes in https://github.com/gristlabs/grist-help/pull/297
Reviewers: paulfitz
Reviewed By: paulfitz
Differential Revision: https://phab.getgrist.com/D4155