src/Config.php
public function push($key, $value)
    {
        $items = $this->get($key);
        if (!is_array($items)) {
            throw new UnexpectedValueException("Expected the target to be array, got " . gettype($items));
        }

        $items[] = $value;
        $this->set($key, $items);
    }
public function push($key, $value)
    {
        $items = $this->get($key);
        if (!is_array($items)) {
            throw new UnexpectedValueException("Expected the target to be array, got " . gettype($items));
        }

        $items[] = $value;
        $this->set($key, $items);
    }
{@inheritdoc}