Pull Request resolves #35252

• I read the Generative AI policy and my contribution is either not created with the help of AI or is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

when a required modal field is left empty, the field is now visibly marked invalid with this fix.
As discussed in issue #35252 for Articles - Categories the issue is no longer reproducible on current branches because Parent Category is optional there, but the issue stil exists on required modal fields for instance User Notes.

Testing Instructions

Navigate to users > users notes > create new
fill user field (select any user ) but leave the category field empty and click save or save&close

Actual result BEFORE applying this Pull Request

form is blocked with the erroe message :
"The form cannot be submitted as it's missing required data.
Please correct the marked fields and try again"
But the visible required field (Category) is not clearly marked invalid

Expected result AFTER applying this Pull Request

Form is blocked.
Category field is visibly marked invalid.

Link to documentations

Please select:

• Documentation link for guide.joomla.org:

• No documentation changes for guide.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed