message: bug: set a default size for templates in thumbnails
diff: @@ -95,7 +95,7 @@ const previewTemplate = ({ mediaPreviewSrc, sourceLink, size, type = 'picture',
  isMediaPreviewLarge: size === 'large',
  isMediaPreviewCompact: size === 'medium',
  isMediaPreviewSmall: size === 'small',
  - thumbSizeClass: `media-size-${size}`,
  + thumbSizeClass: `media-size-${size || 'medium'}`,
  needsProvider: !['default', 'universal'].includes(provider),
  provider,
  }));
  