https://musicbrainz.org/release/ac8d5db2-e4ec-4c39-a787-7b89db702c0a/cover-art is (apparently incorrectly?) set as darkened, and while we do block adding more cover art, we still try to load the existing pieces. Which, of course, works in that example because it's wrongly set to darkened, but it doesn't work on a release that is really darkened (such as https://musicbrainz.org/release/7f8dbdf2-dad9-487c-ba28-d602c532d864/cover-art - which is not set to darkened in MB, see MBS-6567). We should just mention that the release is darkened and not try to load the art at all.
We should also not show a number at all in the cover art tab header.