Reproduction

1. start up brx-saas
2. go to http://localhost:8080/cms/console/?1&path=/content/documents/brxsaas/xpages/home/ and remove from all variants the child node brxsaas:image
3. go to /cms to the homepage and then open the homepage in CM
4. Choose below [page] for edit

Now the 'image field' is not shown and an ERROR is logged"

ERROR http-nio-8080-exec-9 [NodeFieldType.readFrom:56] No values available for node of type 'brxsaas:image' of document at /content/documents/brxsaas/xpages/home/home[2]. This document type cannot be used to create new documents in the Channel Manager.

Issue

In org.onehippo.cms.channelmanager.content.documenttype.field.type.NodeFieldType

  if (values.size() < getMinValues()) {
            log.error("No values available for node of type '{}' of document at {}. This document type cannot be " +
                    "used to create new documents in the Channel Manager.", getId(), JcrUtils.getNodePathQuietly(node));
        }

the actual values for brxsaas:image is 0 and min values is 1 (although the field is not required)

Not a one-off

The same issue will occur if for an existing document type a new compound like an image will be added. Existing documents won't have a node for this issue (only newly added ones since it ends up in the prototype