With "Programmer Art" active, the "Bad Omen" effect has no icon texture. I know why this is, all effect icons, and survival inventory screen textures are stored in the same PNG file. With Programmer Art active, it changes that PNG file to what is it is 1.13.2, so the other effects get the old icons. However, this also deletes the Bad Omen effect texture, and replaces it with the placeholder texture added in that file. To fix this, simply add the Bad Omen icon to that file, and not any others.