[5.1 and 5.2] Multilingual Associations broken if the Option "Multilingual Associations" is "Hide"

[newtastic]

Steps to reproduce the issue

Install a fresh Joomla 5.1 or 5.2 (RC4)
Setup a small Multilingual Site (Activate Filter Plugin, create one or two articles)
Go to Content > Articles > Options > Tab "Editing Layout" > Set the Option "Multilingual Associations" to "Hide"
Go now to Components > Multilingual Associations > Click on an Article > Choose a Target Language

Expected result

See on the left side the Reference Article and on the right side the Target Article.

Actual result

The Joomla Logo shows infinite and the Browser Console shows this:

Uncaught TypeError: o.querySelector(...) is null
http://localhost/j5114/media/com_associations/js/sidebyside.min.js?dafb01:4

System information (as much as possible)

Tested on Joomla 5.1.4 and 5.2 RC4
No additional Extensions

Additional comments

None

[fgsw]

Give the issue a meaningful title. Have a look at other issues where a user know by reading the title what the issue is about.

[brianteeman]

Bug confirmed although I get a different error

sidebyside.min.js?0fbb40:4 Uncaught TypeError: Cannot read properties of null (reading 'remove')
    at HTMLIFrameElement.<anonymous> (sidebyside.min.js?0fbb40:4:2277)Understand this error
sidebyside.min.js?0fbb40:4 Uncaught TypeError: Cannot read properties of null (reading 'classList')
    at HTMLIFrameElement.<anonymous> (sidebyside.min.js?0fbb40:4:3342)

[newtastic]

Also tested the same steps with Joomla 4.4.8 and this works like excepted.