Fixed mysterious import errors about keys

Fixed import errors like:

  • Field [metafields.key]: must be unique within this namespace on this resource – was happening because importing Metafield update, giving Metafield name in different small-BIG letters than already exists.
  • product_id prefix_option is missing – was happening when retrying to import product because Shopify didn’t download some images

If you notice any other strange and unexpected errors during the import, do let me know.