I’m getting an error line 267 in TagController.php

Relating to use of count on a non array/object

This is a PHP 7.2 related issue

If you modify the code
          $context->setTotalChildren(count($children));
          $context->setTotalSiblings(count($siblings));

to

          $children = is_array($children) ? count($children) : 0;
          $siblings = is_array($siblings) ? count($siblings) : 0;
          // Create some additional {blocks:X} variables
          $context->setTotalChildren($children);
          $context->setTotalSiblings($siblings);

This resolved the issue.

There are other instances of count which could potentially cause an error but I’ve not amended those.