Error loading local files

[fredperes]

I tried loading local files:

data-folder="/img/360magnum/"
data-filename-x="magnum-{index}.png"

But get this error:

Uncaught TypeError: Failed to construct 'URL': Invalid URL

b = -1 !== new URL(p).origin.indexOf("cloudimg") ? p : "https://".concat(d, ".cloudimg.io/").concat(g).concat(p);

What am I doing wrong?