Engine error code

Summary:
i got this alert and have no idea how to decipher it. it says “engine error” at the top

Steps to reproduce:

it happened right after i finished winning a battle with kobolds but i don’t know if it has anything to do with it

Expected Results:

Actual Results:
release-687 (x64)
(4635284 Mooi Tolem) (stonehearth:find_seat_and_eat) bad frame transition to “unit_not_ready” from "started"
stack traceback:
[C]: in function 'fn’
stonehearth/services/server/threads/thread.lua:346: in function 'private_msg’
stonehearth/services/server/threads/thread.lua:543: in function '_dispatch_messages’
stonehearth/services/server/threads/thread.lua:403: in function <stonehearth/services/server/threads/thread.lua:384>
[C]: in function 'suspend’
stonehearth/ai/actions/run_effect_action.lua:66: in function <stonehearth/ai/actions/run_effect_action.lua:38>
[C]: ?
[C]: ?
[C]: in function ‘execute’
…arth/ai/actions/get_food_from_container_adjacent.lua:23: in function <…arth/ai/actions/get_food_from_container_adjacent.lua:13>
[C]: ?

[C]: in function 'run’
stonehearth/components/ai/ai_component.lua:553: in function <stonehearth/components/ai/ai_component.lua:537>
[C]: in function 'xpcall’
radiant/modules/common.lua:257: in function 'xpcall’
stonehearth/components/ai/ai_component.lua:537: in function '_thread_main’
stonehearth/services/server/threads/thread.lua:273: in function <stonehearth/services/server/threads/thread.lua:270>
[C]: in function 'xpcall’
radiant/modules/common.lua:257: in function 'xpcall’
stonehearth/services/server/threads/thread.lua:270: in function 'f’
radiant/lib/env.lua:15: in function <radiant/lib/env.lua:14>

Notes:
it’s all greek to me… but it did not seem to have an ill effect on the game.

Attachments:

Version Number and Mods in use: alpha 19 release 687

System Information: