InvalidTemplateParam

A template argument violates the declared bounds of the type parameter.

Example

<?php
/**
 * @template T of Countable
 * @param T $collection
 */
function count_items($collection): int {
    return count($collection);
}

count_items('hello'); // string does not satisfy Countable bound

How to fix

Pass a value that satisfies the template bound, or loosen the bound if appropriate.