Merge init() configuration table with default configuration

[mizlan]

With an init.lua file like the following,

stackline = require "stackline"
stackline:init {
  appearance = {
    offset = {
      x = 10
    }
  }
}

I see many errors in the Hammerspoon console reporting that I've failed to set a number of different fields (the other configuration options). However, in this case I'd expect the unset fields to take on the values that are the default (i.e., if I were to just have init() with no table, the arguments that would be used in place). It seems like that's not the case, although maybe I am misconfiguring something here.