When the multivalue element is disabled, input is impossible, so no empty item should be added to the element.
Add a disabled multivalue element to a form.
Added in third commit:
Add an extra option #add_empty (supposed to be 1 or TRUE by default) which can be set to 0 or FALSE to not add extra items, also when the element isn't disabled.
Needs review
1.0
Code
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
This patch does apply on beta6, but throws a notice:
Warning: Undefined variable $max in Drupal\multivalue_form_element\Element\MultiValue::processMultiValue() (line 234 of modules/contrib/multivalue_form_element/src/Element/MultiValue.php).