OptionalcatalogRecords filed by an earlier build under a reference this one reads differently,
and so under another paper's id (currentReference, issue #25).
Catalog rows with no record file.
Record files with no catalog row.
False before the first sync: then only the volumes are checked.
Optionalorphaned_Archived documents no record refers to, when asked for (orphanedBlobs): what
records removed by hand leave behind. Absent when not asked, or when a record could
not be read.
macOS ._* and .DS_Store files anywhere in the corpus and the blob store.
What a sync would refuse, or what makes the corpus incomplete.
Absent when the catalog or the record files could not be read (
problemssays why).