IBX-2814: Returned null instead of empty array when there are no child nodes

[ViniTou]

Question	Answer
JIRA issue	https://issues.ibexa.co/browse/IBX-2814
Bug/Improvement	yes
New feature	no
Target version	latest stable for bug fixes, master for new features
BC breaks	yes
Tests pass	yes
Doc needed	yes (this should probably be mentioned somewhere)

TODO:

• Implement feature / fix a bug.
• Implement tests.
• Fix new code according to Coding Standards ($ composer fix-cs).
• Ask for Code Review.

[dew326]

Shouldn't we change checks in our custom tags twig templates? I know this is not a case in this version because AlloyEditor works differently than CKEditor but I think we should have twigs prepared for null.

[konradoboza]

Hence this PR is targetting ezplatform-richtext I assume version 3.3 is also affected - worth mentioning in the ticket.

[ViniTou]

@dew326
It works fine with current state of templates, as it simply adds empty html attribute.

@konradoboza @micszo
This issue is not reproducible on 3.3 as, Darek mentioned, AlloyEditor skips empty keys. But since it is technically possible to replace AE with CKEditor, and overall that solution helps us avoiding strange situations generally, I fixed it at 3.3.
So at 3.3, all you need to check if that it didnt broke anything.

[micszo]

Retested on Ibexa DXP v3.3 & v4.