Google reports the following warnings:

Either "offers", "review", or "aggregateRating" should be specified. But the microdata for the site is generated by Osclass:


{
  "@context": "https://schema.org/",
  "@type": "Product",
  "name": "some name",
  "image": "https://website/0.",
  "description": "some description...",
  "brand": "Osclass",
    "offers": {
    "@type": "Offer",
    "itemOffered": "Name",
    "url": "https://website/some-location",
        "price": "0",
    "priceValidUntil": "2024-02-26",
    "availability": "https://schema.org/InStock"
  },
  "aggregateRating": {
    "@type": "AggregateRating",
    "ratingValue": "5",
    "bestRating": "5",
    "worstRating": "0",
    "ratingCount": "1",
    "reviewCount": "1"
  }
 }
Looking through the Delta theme files, I noticed that there's the following code there (in themes/delta/item.php):

    <!-- GOOGLE RICH SNIPPETS --> 
  <span itemscope itemtype="http://schema.org/Product">
    <meta itemprop="name" content="<?php echo osc_esc_html(osc_item_title()); ?>" />
    <meta itemprop="description" content="<?php echo osc_esc_html(osc_highlight(osc_item_description(), 50
0)); ?>" />
    <?php if(osc_count_item_resources() > 0) { ?><meta itemprop="image" content="<?php echo $resource_url;
 ?>" /><?php } ?>
  </span>

There's no "offers", "review", or "aggregateRating" specified. . I think this code should be removed or some entries added to it, to fix the google warning.

Also it looks like there are two microdata blocks -- one generated by Osclass, and the other generated by the theme. Should it be in this way?
 

You csn remove this code if you decide that osclass generates structured data.

OK, I removed it, and it looks like google doesn't complain about it anymore.

Nice, good job