TypeError: krsort(): Argument #1 ($array) must be of type array, null given in krsort()

tnx

Bulk reopen.

This needs better steps to reproduce the problem, specifically in regard to the configuration of the entities involved. Does the node have the IEF field or the block? Are you placing the block on the node type's default layout or customizing the layout of a single node? Does the IEF field (whatever entity it's attached to) need to have entities referenced or be empty? I've tried every combination that I can think of and can't reproduce the problem. I'll admit that the code looks like it has this issue. But if it can't be reproduced then that's a problem because if it's a bug then this also needs tests.

Ohoh, i remember well when i coded that. Context:

    $widget_states =& $form_state->get('inline_entity_form');
    // Widget states can be in an arbitrary order depending on user's form
    // interaction. We sort them lexicographically in reverse order to get inner
    // forms before outer forms, to ensure inside-out saving of entities.
    // @see \Drupal\inline_entity_form\Plugin\Field\FieldWidget\InlineEntityFormBase::makeIefId
    krsort($widget_states, SORT_STRING);

No guarantee that there are widget states at this point. So it's as simple as this one with no regression risk:

 $widget_states =& $form_state->get('inline_entity_form') ?? [];

Ah, i forgot the

=&

which makes #9 impossible and mandates the extra line from #3.