Matthew Oros

It seems to be working for me on `v0.17.1` on Windows 10 at least. It also seems to be working correctly on `html` and `pdf` exports as well. 

I believe type `CircleLayerSpecification.filter` should be type `FilterSpecification | ExpressionSpecification` instead of just `FilterSpecification`

The problem seems to be here in `git.ts` ```typescript if (typeof callback !== 'function') callback = () => { return; }; if (!/\.git$/.test(repo)) repo += '.git'; const exists = this.exists(repo);...