Products with no price break the product selector

[Aljullu]

Similarly to #2551, I'm only able to reproduce this issue in a specific server, but not in local.

To Reproduce

1. Create a product (or modify an existing one), so it doesn't have a price.
   
2. Create a page and add a Hand-Picked Products block or a Featured Product block. I guess all blocks which have a product selector will have this issue.
3. Notice the block placeholder shows a 'The response is not a valid JSON response.' error message:
   

The API response is:

Warning: A non-numeric value encountered in /usr/home/.../web/wp-content/plugins/woocommerce-gutenberg-products-block-2.6.0/src/StoreApi/Schemas/AbstractSchema.php on line 243

... /* the error message is repeated three times per each product with no price */

[ /* correct JSON data here */ ]

My guess is that we need to return early in:
https://github.com/woocommerce/woocommerce-gutenberg-products-block/blob/master/src/StoreApi/Schemas/AbstractSchema.php#L240
if $amount is not a number.

[nerrad]

Probably related to this.

[Aljullu]

I couldn't find yet why this error is only occurring in my server but not in local.

Basically, the $amount value is an empty string (it comes from here). wc_format_decimal() doesn't modify it, so we end up with "" * ( 10 ** 2 ), the server shows a warning with this calculation while local, doesn't.

Server is PHP 7.4 while local is 7.3.

Doing this change fixes the issue:

-wc_format_decimal( $amount ) * ( 10 ** $decimals ),
+floatval( wc_format_decimal( $amount ) ) * ( 10 ** $decimals ),

[nerrad]

wc_format_decimal removes all decimals etc from the string right? So could it just be absint?

[Aljullu]

@nerrad I don't think we can use absint here, wc_format_decimal might return strings representing decimal numbers (ie: "9.99").

[nerrad]

Hmm, I saw this code doc for wc_format_decimal without looking at the code, seems like it's not accurate then:

Sanitize, remove decimals, and optionally round + trim off zeros.

[Aljullu]

Yeah, I'm a bit confused by that remove decimals from the method description, but rounding is controlled by the $dp argument. Leaving it undefined (so it defaults to false) means no rounding happens.

I tested it locally, but the tests are also quite handy to see how it works: https://github.com/woocommerce/woocommerce/blob/master/tests/legacy/unit-tests/formatting/functions.php#L297.