Product Gallery: Address the edge case when Product Image is not set but Product gallery images are

[danieldudzic]

Describe the bug

Currently in the following situation:

The Product Gallery block will:

• Hide the Thumbnails
• Still output the Next/Previous Buttons and the Pager
• The first Large Image image will be blank

To reproduce

Steps to reproduce the behavior:

1. With a block theme, open Appearance > Editor.
2. Open Templates > Single Product.
3. Select Convert to Blocks if you are using the Classic Templates.
4. Add the Product Gallery block.
5. Edit a product and make sure the Product Image is not set but some Product gallery images are.
6. Notice the broken behavior on the front end.

[danieldudzic]

@jarekmorawski @roykho In the event that the Product Image is not set but some Product Gallery images are present, which of the following behaviors should be preferred?:

• Display an empty Large Image.
• Display an image Placeholder as the Large Image.
• Hide the Thumbnails (and Pager and Next/Prev buttons) altogether.
• Set the Large Image to the first of the Product gallery images and display Thumbnails, Pager and Next/Prev buttons normally.

FYI: The legacy WooCommerce Single Product Gallery hides the thumbnails and pagination and just displays the placeholder:

[jarekmorawski]

Great question. Thanks for keeping an eye out for such details. I'd display the image placeholder as well as the Thumbnails and the Prev/Next buttons. It's a temporary solution because, in the new product editing UX, the large image is set automatically.