[BUGFIX] Prevent JavaScript error on changing single option group fields

A check in the FormEngine JavaScript component
is fixed, preventing a corresponding error when
changing the value of a single option group field,
e.g. the "content_from_pid" field in pages.

Additionally, a wrong selector, leading to a
ReferenceError, is fixed as well.

Resolves: #97342
Related: #95137
Releases: main, 11.5
Change-Id: I8c27f9ee4eddb032ec51ef66db99da3bf3c5a8d3
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/74253


Tested-by: core-ci <typo3@b13.com>
Tested-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Oliver Bartsch <bo@cedev.de>