src/PriorityQueue.php
public function insert($value, $priority)
    {
        if (!is_int($priority)) {
            $value    = $priority;
            $priority = self::PRIORITY_NORMAL;
        }

        parent::insert($value, [$priority, $this->serial--]);
    }
public function insert($value, $priority)
    {
        if (!is_int($priority)) {
            $value    = $priority;
            $priority = self::PRIORITY_NORMAL;
        }

        parent::insert($value, [$priority, $this->serial--]);
    }
Fix: "Note: Multiple elements with the same priority will get de-queued in no particular order."

@param mixed $value    Middleware name
@param mixed $priority Middleware priority

@return void