Fix for Magento 2 (tested on v2.1.6).
It fixes the case when there is no a required option swatch image in media (and maybe other cases for lost images).
It's quite useful after database migration during development.
composer require --dev onepica/mage2-dev-no-image
On initiate an image the module will create small placeholder (20x20 px) by the same image path.
Please be aware this module will overwrite the class Magento\Framework\Image.