The IdGenerator was recreated each time and had a high likelihood of conflicts. Invitably after adding dozens or hundreds of icons you'll start seeing the CSS class replaced and overridden.
The solution is to do like elsewhere: have 1 const that is loaded on first import of the file and keeps a global track.
Side note is that it'd be a good idea to cache CSS rules with the same iconPath so we don't create lots of additional rules unnecessarily. If we reuse the same icon a bunch we should cache them - #2524 is tracking this.
