So, one of my hearthlings met an unfortunate goblin-related end relatively early on. I then immediately went to go investigate this Party system in order to prevent further mishaps (buddy system, guys!).
The dead hearthling was still listed in the Party assignment screen, although the name was blank and clicking the button to add them to the party did nothing but pop up a lua error (which I’m sorry to say I don’t have a screenshot of). The dead hearthling did not end up assigned to either Party 1 or Party 2, but remained an option for either.
Either dead hearthlings need to be removed from the party screen, or they need to rise from their graves to defend the village at need.