validateActive example

if (false === $this->isOk()) {
            throw new RuntimeException('Cannot retrieve stream due to upload error');
        }

        if ($this->isMoved()) {
            throw new RuntimeException('Cannot retrieve stream after it has already been moved');
        }
    }

    public function getStream(): StreamInterface
    {
        $this->validateActive();

        if ($this->stream instanceof StreamInterface) {
            return $this->stream;
        }

        /** @var string $file */
        $file = $this->file;

        return new LazyOpenStream($file, 'r+');
    }