White fill shows as blank with no error message (threshold doesn't work for that case)

[odinndagur]

If you have a layer with the correct name and artwork on it but it's only got white fill it just shows up as blank. I think it's because of the threshold. Attached is a zip file with just one svg file and one kicad_pcb file generated from that svg.

Might be good to add a message warning users or try changing the fill if it turns out blank when processing? issue-gingerbread.zip