epubveri for Sigil 0.1.1 is up, and it is the two you found plus one you did not.
https://github.com/veripublica/epubv...g/sigil-v0.1.1
DNSB, the summary line. A result about the book as a whole names no file, and I said so with an empty string. That is the one value Sigil's result table reads as a mistake rather than as an absence: it resolves the bookpath to a resource and, failing that, prints "Invalid Book Path Provided" for an empty one and the path itself for anything else. It now sends a single space, which is neither empty nor a path, so the File column comes out blank. Doitsu's None clears it too, and finding the line was his; I went with the space only because None reaches that column as the literal word. The same empty string was in seven other places, including every finding epubveri makes about the container rather than about a file, so this was waiting for a real book as well.
DNSB, the icon. Shipped, an svg with a png beside it, which is the order Sigil looks in. A filled tile rather than a line drawing, because Sigil has a dark theme and a single-colour outline vanishes into one of the two.
And the one nobody reported. Testing this build, content.opf said line 95 and the cursor landed on 96. The OPF only. I had been overwriting the copied OPF with get_opf, which is a rebuild from Sigil's model: it sorts the manifest by id and rewrites every entry. My line numbers were correct for that rebuild and for nothing else. On the book that caught it, the cover entry sits at line 91 in the file, 95 in the rebuild, and 96 in what Sigil was displaying. Three numbers for one line, and the two a user can see were not the one I sent. The substitution was there so unsaved manifest and spine edits would still be validated, and it was never needed: the OPF is not a manifest item, so readotherfile already hands back the live rebuild when there are unsaved OPF edits and the file from the ebook root otherwise. Removing it keeps both. One limit stays, and I would rather say it than have someone find it: with unsaved OPF edits, positions in the OPF refer to Sigil's rebuild rather than to the text on screen. I cannot see a way to ask a plugin what Code View is holding.
PeterT — thank you, that is the first Linux report. With DNSB on Windows, the line in 0.1.0's notes about nobody having run it outside macOS is now answered on all three.