I'm having some issues using the symbolPreview for any fill symbols. it works fine for simple-marker, but if I use a simple-fill symbol, nothing renders and I get a 404 error for https://js.arcgis.com/4.6/esri/symbols/patterns/solid.png
var s = new Symbol({
type: 'simple-marker',
color: 'red',
size: 12
}); //this works.
var s2 = new Symbol({
type: 'simple-fill',
style: 'solid',
color: 'red'
}); //this doesn't work.
symbolPreview.renderPreviewHTML(s, {
node: element.getElementById("preview"),
size: s.size ? s.size : 12
});