When Forest URL is a subdirectory, preview doesn't work(?) #27

Just to exercise this a bit, I tried out https://github.com/samtoth/agda-synthetic-categories, which is configured like so:

[forest]
trees = ["trees"] # The directories in which trees are stored
url = "https://samtoth.github.io/agda-synthetic-categories/"
assets = ["assets"]
home = "index"

Running forester, I can't figure out how to actually access the preview. localhost:8080/preview/ and localhost:8080/agda-synthetic-categories/preview/ both result in Router: no match.