Flash of missing image when lazy loading

A comment from the maintainer in 🐛 Lazy load images not replaced correctly Active :

Regarding the "flash", we unset the src for lazy loaded images to prevent them from being loaded by the browser. It prevents duplicate images being loaded in some cases. However, if an image is in the viewport, removing the source can cause this flash. I think we might be able to figure something out to solve this.

This least stops the broken image from appearing but still there is a small flicker

I tested the changes and the broken image doesn't appear anymore. In a project we added this to make the flicker stand out less, but it might be too opinionated to add to the module:

img[data-srcset] {
    opacity: 0;
    transition: opacity 150ms ease;

    &[data-loaded="1"] {
        opacity: 1;
    }
}