Prevent rendering of RichTextBlock without content (#2585)

Currently, blocks using the `PreviewSkeleton` are rendered empty in the
site if they do not contain any content. This causes unwanted HTML tags
in the site. This change prevents these blocks from being rendered
without content.

---------

Co-authored-by: Stefanie Kaltenhauser <[email protected]>
Co-authored-by: Johannes Obermair <[email protected]>

.changeset/wise-mirrors-rescue.md

@@ -0,0 +1,10 @@
+---
+"@comet/cms-site": patch
+---
+
+Prevent rendering of empty blocks in `PreviewSkeleton`
+
+Previously, in non-preview environments, `PreviewSkeleton` would still render its children, even if `hasChanges` was set to `false`, causing unwanted empty HTML tags in the site.
+For instance, an empty rich text block would still render a `<p>` tag.
+Now, the children will only be rendered if `hasContent` is set to `true`.
+Doing so removes the need for duplicate empty checks.

packages/site/cms-site/src/previewskeleton/PreviewSkeleton.tsx

@@ -53,6 +53,11 @@ const PreviewSkeleton = ({
             );
         }
     }
+
+    if (!hasContent) {
+        return null;
+    }
+
     return <>{children}</>;
 };