PHP Fatal Error – yii\base\ErrorException

     * @param  string the operation initiating the creation
     *
     * @return resource
     *
     * @throws RuntimeException
     *
     */
    private function createImage(BoxInterface $size, $operation)
    {
        $resource = imagecreatetruecolor($size->getWidth(), $size->getHeight());
 
        if (false === $resource) {
            throw new RuntimeException('Image '.$operation.' failed');
        }
 
        if (false === imagealphablending($resource, false) || false === imagesavealpha($resource, true)) {
            throw new RuntimeException('Image '.$operation.' failed');
        }