Header Tag Product Schema JSON-LD and Google

[Philo2005]

While optimizing my Phoenix Shop with Google Search Console I found the Header Tag Product Schema JSON-LD
which finally enables Products tab in Google Search Console.

Once this script is enabled it shows in the header of the product_info.php code additional informations related to the product.

Example:
https://www.attias.ch/ishop/product_info.php?products_id=2152&language=en
shows:
{"@context":"https:\/\/schema.org","@type":"Product","name":"CH 1882 Ziffermuster weisses Pap. 53b (45) gestempelt Wyl SG","image":"https:\/\/www.attias.ch\/ishop\/images\/CH1882Ziffer53No1.jpg","url":"https:\/\/www.attias.ch\/ishop\/product_info.php?products_id=2152","description":"Switzerland 1882, Ziffermuster, weisses Papier, Kontrollzeichen Form A, 2 Rappen (SBK 53b, Michel 45), 2 Rp. hellolivbraun, sauber gestempelt WYL SG, 08.12.1882, farbfrisch und einwandfrei gez\u00e4hnt...","mpn":"CH1882-53No1","offers":{"@type":"Offer","priceCurrency":"CHF","price":"300.00","availability":"https:\/\/schema.org\/InStock","seller":{"@type":"Organization","name":"Philatelie Attias, CH-5620 Bremgarten AG"}},"manufacturer":{"@type":"Organization","name":"CH"}}

Google Search Console sent me an E-Mail telling me the following warnings:

Search Console has identified that your site is affected by 6 Products issues:

Top Warnings

Warnings are suggestions for improvement. Some warnings can affect your appearance on Search; some might be reclassified as errors in the future. The following warnings were found on your site:

Missing field "url"

Missing field "review"

Missing field "aggregateRating"

Missing field "brand"

Missing field "sku" 

This will appear for all my products.

Somebody found a solution for These issues or has any Idea how to get rid of them? 

There is also an additional header tag called
Breadcrumb Schema JSON-LD,
but no description for what it is?

[BrockleyJohn]

First off, a warning on the schema checker is not an issue unless you have data which is useful for SEO and not output.

You can test a specific url online here

https://search.google.com/structured-data/testing-tool

Your example shows 3 warnings - lack of review information and no end date for the price. This is entirely to be expected if you have no reviews and don't have a special price with an end date set.

Everything looks good to me.

[Philo2005]

Okay thank you @BrockleyJohn