Leaving a viewer image while it was still loading (Previous, Next, the
arrow keys, Retry) deferred the inline Viewer.js destroy() until the
image's view settled, failed or a 10 s fallback ran. Before its image
loads Viewer.js has not built, so nothing could settle: the stage
dropped the image, the late load ran Viewer.js's build() on an image
without a parent, and getComputedStyle(null) threw a page error
("Argument 1 is not an object" in Firefox, "must be an instance of
Element" in WebKit). Under CI load this failed "collection viewer
follows filtered loaded order beyond mounted cards".
A viewer that is not ready yet is now destroyed at once, which cancels
its pending build, and its image src is released. A built viewer with
a still-loading view keeps the existing deferral.
Vito Sansevero
429b3a849e