Yesterday's example was meant to be:
 

holster.get("hello").get("world!").put({
  things: "I want to add",
  which: {
    can: "also have nested objects",
  },
}, console.log)

Which I decided to test before adding to the post, and of course it didn't work! I then realised I hadn't tested chained gets at all, so I modified the example to something that worked and then looked at the chained get problem today.

I've just pushed a fix for it, which thankfully also cleared up some edge cases in the code around resolving keys, so it now works and the code is nicer too.