PHP Fatal error: Nesting level too deep - recursive dependency? in 10.5.2

I've found this has to do with the |last filter in twig.

This turned out not to be a Drupal core regression but a side-effect of the Twig upgrade to 3.21.x in Drupal 10.5.2. The newer Twig runtime iterates Traversables differently. Using the |last filter on field item lists or render arrays (which are lazy iterables) now causes recursion and “Nesting level too deep” errors.

The fix is to avoid |last (or |length) on render arrays/field iterators. Instead, use loop.last inside a for loop or compute the last item in a preprocess hook and print that in the template.

I was specifically using |last inside a {% for item in items %} loop, likely hitting this with the embedded Twig upgrade surfacing a fragile Twig pattern (|last on lazy/recursive iterables)

Closing this since the error is due to a Twig behavior change, not a bug in Drupal core itself.

Note, in case anyone else hits this error, here was the problem and solution for me.

Before where `|last` caused the recursive twig error:

{% for item in items %}
  {{ item.content }}{% if item != items|last %} | {% endif %}
{% endfor %}

After, which resolved the error:

{% for item in items %}
  {{ item.content }}{% if not loop.last %} | {% endif %}
{% endfor %}

Replacing |last with loop.last worked. I'm adding a pipe between list items in a twig field template, but don't want it on the last item. I use ` ` because a plain empty space is removed with html-minification.