fix: typerror on hide_fields (backport #41517)

[mergify[bot]]

Internal Ref: 14753

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This is an automatic backport of pull request #41517 done by Mergify.

[mergify[bot]]

Cherry-pick of deb9766f2ac1e28b2f7d1e9ec6657b123c16cd68 has failed:

On branch mergify/bp/version-14-hotfix/pr-41517
Your branch is up to date with 'origin/version-14-hotfix'.

You are currently cherry-picking commit deb9766f2a.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
    both modified:   erpnext/accounts/doctype/purchase_invoice/purchase_invoice.js

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[frappe-pr-bot]

:tada: This PR is included in version 14.70.1 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket: