I post this question for the second time because the post prior to this one won't open for some reason.

We use Joomla 3.9.12 and Form2Content 6.17.4
We have upgraded from PHP 7.1 to PHP 7.2

All articles generated with Form2Content are OK but when we make a new a article we get a few notices which start with:
Notice: Undefined offset: 0 in /home/sites/.../nameoftemplate_sjabl_intro.tpl.php
I think it has something to do with:

{if $AFBEELDINGEN_IMAGES[0]}</div>{/if}

If I add an image there is no problem.
If I don't add an image the Notice becomes visible.
If I select the article and click on the button "Refresh" the notice is gone.

What could be wrong with the code?

{if $AFBEELDINGEN_IMAGES[0]}</div>{/if}