No longer working. Replaced it with custom user script for greasemonkey (I had it installed anyway for many user scripts):
https://gist.github.com/ner00/ec9ae47e202b8e99f19be44a5af6baf3/raw/viewimage.user.js
(taken from: https://github.com/bijij/ViewImage/issues/268#issuecomment-1476294452 )