Sandcastle link here:
Long story short, tracked down a weird Cesium bug/feature and repro’d it more simply in the sandcastle link. Create a custom imagery provider from scratch, and make requestImage return a brand new unmodified Image element. No src value at all. When you do this, instead of being, say, transparent or something, it causes a bunch of WebGL warnings to fill the console.
“WebGL: INVALID_VALUE: texImage2D: no image”. Of course it’s totally correct, there’s no image. But maybe the rendering process could handle this a bit more cleanly? Maybe a sanity check somewhere to see if you got an Image w/ an empty src and bubble out a specific message about that?
Additionally if you don’t set a width or height on the Image element, you’ll crash out the rendering process but that’s kind of expected I suppose. But this does give you a proper explanation message.