Destroying an unbuilt inline Viewer.js at once (429b3a8) is not safe in
one state. Viewer.js's own cancel removes its image listeners only while
`image.complete` is false, so an image that had finished downloading
with its load event still queued kept them. Closing the viewer then
released the src, the queued load built Viewer.js anyway, and its first
view found no listed image: "can't access property querySelector, c is
undefined" (workspace-history.spec.mjs:222 on Firefox in CI).
The viewer now constructs Viewer.js from its own load listener, which the
media scope removes when the image is left. Before the load no Viewer.js
exists, so leaving the image only releases its src; after it Viewer.js
sees a complete image and only its zero-delay build is pending, which
destroy() cancels. Transforms report Viewer.js as unavailable only when
it did not load at all.
Vito Sansevero
10864369ce