Issue #3239704 by shevchess: Breaks Drupal core "Convert" image style effect...

    // Don't try to generate file if source is missing.

    if (!file_exists($image_uri)) {

      // If the image style converted the extension, it has been added to the

      // original file, resulting in filenames like image.png.jpeg. So to find

      // the actual source image, we remove the extension and check if that

      // image exists.

      $path_info = pathinfo($this->streamWrapperManager->getTarget($image_uri));

      $converted_image_uri = sprintf('%s://%s%s%s', $this->streamWrapperManager->getScheme($image_uri), $path_info['dirname'], DIRECTORY_SEPARATOR, $path_info['filename']);

      if (!file_exists($converted_image_uri)) {

        $this->logger->notice('Source image at %source_image_path not found while trying to generate derivative image.', ['%source_image_path' => $image_uri]);

        return new Response($this->t('Error generating image, missing source file.'), 404);

      }

      else {

        // The converted file does exist, use it as the source.

        $image_uri = $converted_image_uri;

      }

    }

    // Check that the style is defined, the scheme is valid, and the image

    // derivative token is valid. Sites which require image derivatives to be