Engine Error when completing goblin contractors task

Summary: Engine Error when completing goblin contractors task: invalid out_edge specification in function ‘assert’

Steps to reproduce:

  1. Place Elite Gong.
  2. gather materials for goblin contractor.
  3. Hand materials in to goblin contractors.

Expected Results: Receive recipe for Red Gong (I think?)

Actual Results: Engine Error

Notes:

release-687 (x64)
…arth/services/server/game_master/controllers/arc.lua:204: invalid out_edge specification.
stack traceback:
[C]: ?
[C]: in function ‘assert’
…arth/services/server/game_master/controllers/arc.lua:204: in function ‘_convert_out_edge_to_edgelist’
…arth/services/server/game_master/controllers/arc.lua:263: in function ‘_trigger_out_edge’
…arth/services/server/game_master/controllers/arc.lua:255: in function ‘trigger_next_encounter’
…ontrollers/encounters/collection_quest_encounter.lua:238: in function ‘_finish_encounter’
…ontrollers/encounters/collection_quest_encounter.lua:416: in function <…ontrollers/encounters/collection_quest_encounter.lua:413>

release-687 (x64)
c++ exception: lua runtime error
stack traceback:

Attachments:

Version Number and Mods in use: release-687(x64), vanilla

System Information: Windows 10 Home x64 | AMD Phenom II 1090T | 8gb Ram | GTX 670