Weird ReservedWord "Parameter cannot be never" when using Laravel collections about psalm HOT 3 CLOSED

<?php

/**
 * @template TKey of array-key
 * @template TValue
 */
interface Arrayable
{
    /**
     * Get the instance as an array.
     *
     * @return array<TKey, TValue>
     */
    public function toArray();
}

class Arr
{
    /**
     * Run a map over each of the items in the array.
     *
     * @param  array  $array
     * @param  callable  $callback
     * @return array
     */
    public static function map(array $array, callable $callback)
    {
        $keys = array_keys($array);

        try {
            $items = array_map($callback, $array, $keys);
        } catch (ArgumentCountError) {
            $items = array_map($callback, $array);
        }

        return array_combine($keys, $items);
    }
}

/**
 * @template TKey of array-key
 *
 * @template-covariant TValue
 */
class Collection
{
    /**
     * The items contained in the collection.
     *
     * @var array<TKey, TValue>
     */
    protected $items = [];
    
     /**
     * Create a new collection.
     *
     * @param  Arrayable<TKey, TValue>|iterable<TKey, TValue>|null  $items
     * @return void
     */
    public function __construct($items = [])
    {
        $this->items = $this->getArrayableItems($items);
    }
    
    /**
     * Merge the collection with the given items.
     *
     * @param  Arrayable<TKey, TValue>|iterable<TKey, TValue>  $items
     * @return static
     */
    public function merge($items)
    {
        return new static(array_merge($this->items, $this->getArrayableItems($items)));
    }
    
    /**
     * Run a map over each of the items.
     *
     * @template TMapValue
     *
     * @param  callable(TValue, TKey): TMapValue  $callback
     * @return static<TKey, TMapValue>
     */
    public function map(callable $callback)
    {
        return new static(Arr::map($this->items, $callback));
    }
    
   /**
     * Results array of items from Collection or Arrayable.
     *
     * @param  mixed  $items
     * @return array<TKey, TValue>
     */
    protected function getArrayableItems($items)
    {
        if (is_array($items)) {
            return $items;
        }
        
        return (array) $items;
    }
}

$suffixHeaders = ['foo', 'bar'];
(new Collection())
    ->merge($suffixHeaders)
    ->map(fn (string $header) => ucfirst($header));